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Crusader 1996 454XLT Hot start problems (ECUs issue?}

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Captainfredsr

New member
I have two 1996 454XLT with throttle bodies with engines under 30 hours and both will start but will not idle or stay running after I run the boat for 1 to 2 hours. Both ack like they have gas supple issue, but when running the pumps are at the required 18-20 pressure, GPH and are Crusader specs. I wrapped all steel fuel lines with "heat wrap material". Both bilge blowers and air supply tubes checked. Two separate gas tanks and gas was check. Rebuild one Throttle body, replaced all sensers, fuel pumps {twice}, filters, two new distributers, and tank supply hoses. Otherwise they start great and when running the engines are fantastic through the RPM ranges. Running engine temperatures are great. I have taken the time to switch parts between the the two engines. I used a :heat gun" on both engines and temperatures are as expected. Question then would be the original ECU controllers (47017 or 47049) be the problem when they get to engine temperature? After about 2 hours sitting they both start perfectly. This problem was also with the original engines prior the purchasing two rebuilds but just appeared 2 years ago otherwise I have owned the boat for 12 years without this problem. ECU are not available, so if you think they are a problem, can they be tested, repaired or is there a aftermarket replacement?
Thanks; Captain Fred
 
If the problem was there before and after the rebuilds, I'd suspect something that wasn't changed...relays come to mind.

If changing them doesn't make a difference, you can get a scan tool and check the operating parameters in real-time...could be something is off but not failed enough to set the CEL...

If it is the ECU's there are several places that will repair what you have or sell you replacement units...a web browser will find several in short order...what you have is a MEFI-1 or -2...you can tell by removing the mounting bolts and find the GM number on the back of the ECU...
 
makomark said:
If the problem was there before and after the rebuilds, I'd suspect something that wasn't changed...relays come to mind.

If changing them doesn't make a difference, you can get a scan tool and check the operating parameters in real-time...could be something is off but not failed enough to set the CEL...

If it is the ECU's there are several places that will repair what you have or sell you replacement units...a web browser will find several in short order...what you have is a MEFI-1 or -2...you can tell by removing the mounting bolts and find the GM number on the back of the ECU...
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I have the Diacom Dynamistic program for these models and running engine data look normal and no codes. I did found the GM number on the ECU back. You mentioned CEL, What is CEL?
 
Check Engine Light....not everybody installed them, especially with the first couple years of electronic control...

with no codes, the CEL will be off, if equipped.
 
Captainfredsr said:
I have the Diacom Dynamistic program for these models and running engine data look normal and no codes. I did found the GM number on the ECU back. You mentioned CEL, What is CEL?
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makomark said:
Check Engine Light....not everybody installed them, especially with the first couple years of electronic control...

with no codes, the CEL will be off, if equipped.
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OK I should have known and they do have them on the pigtail interphase socket and they have been off yet its worth another look. Thank You!
 
FWIW, ECU's rarely fail and most are due to abuse, on the ones I have seen.

I'd be more inclined to focus on the fuel pump...given the age of things, it's possible the fuel pump isn't getting full battery voltage and not running (no alternator output) won't help.

It could also be a simple as the anti syphon valve has corroded a bit and its cracking pressure has risen.

What's really weird is it happens to both engines...

Have you check the fuel pressure with the engines off and cold?

can you plumb a vacuum gague into the unused OUTLET port on the filter?
 
makomark said:
FWIW, ECU's rarely fail and most are due to abuse, on the ones I have seen.

I'd be more inclined to focus on the fuel pump...given the age of things, it's possible the fuel pump isn't getting full battery voltage and not running (no alternator output) won't help.

It could also be a simple as the anti syphon valve has corroded a bit and its cracking pressure has risen.

What's really weird is it happens to both engines...

Have you check the fuel pressure with the engines off and cold?

can you plumb a vacuum gague into the unused OUTLET port on the filter?
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Weird is an understatement! We purchased the boat in 2009 and with no starting problems till 2022 so its Just driving us crazy! I appreciate your comments on the abuse and there are some people that are hammer and vise-gripe "so called" mechanics. I am a stickler with anything I do and use only Crusader parts or OEM equals. My engines look as if they are new and well maintained. Now the anti-syphon valves were not on ether tank but we installed one on the Port tank and both tanks have new supply hoses ( custom made Parker Hannifin marine M,P with installed end fittings) and matting fittings, to the engines and shut-off valves inspected in good shape. Fuel pressure, yes with the engines off and by-passing the ECU at the relay (which is new) pressure checks good. Will recheck the voltage again but hasn't been a problem. Installing a test vacuum gauge is tricky because of the steel tubing around the filter head (also new) but not impossible, just not that easy but I understand what to look for. ( interesting Idea!) HERE IS A THOUGHT: I made up a wiring harness with a switch to go direct from the battery to the pump of which I have an extra plug for it. When one engine fails to start, I will unplug the pump from the harness and install it and on "crank" I will turn the pump "ON" and see if the engine stays running. That way if it doesn't I can turn the pump "off" Not sure how the ECU will react to the pump being "unplugged. Your opinion? Weather over the last 3 days have been terrible so haven't been able to get the boat out of the slip to get it tested. Most likely it be towards the end of the week for a run. So stay tune as the saga continues!
 
I am all for good parts...but don't feel compelled to pay the premium for a crusader label on the box...

If you consistently have good fuel pressure, then there isn't much need to do the vacuum test on the suction side...adequate output only happens with adequate input..
 
Just to be clear, you have measure the fuel pressure prior to and during the "engine cuts out after 1-2 hours of running" event?
 
makomark said:
Just to be clear, you have measure the fuel pressure prior to and during the "engine cuts out after 1-2 hours of running" event?
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Thanks, that is why I started to research the Crusader numbers to convert to OEM numbers or a quality aftermarkets but as you know prices and availability have gone crazy for these older engines (and everything else). My 50+ years in diesel parts helps with this task! We have check pressure over time, but I will re-check this week to get current information. Any comment on the testing with the remote wiring harness test? Thanks!
 
I don't believe the ECU will have any indications that your harness is connected...it just turns the fuel pump on and off and never verifies the fuel pump state (this changes as things mature, to a certain extent). The harness test, as I understand you decription, will eliminate the ECU control of the relay and the relay's contacts...would be good data to have given where you are in the debug process...

I think you will have to monitor the fuel pressure and hopefully have the event occur at the same time...This will help to identify the stalling as a fuel issue and not a spark issue... having a clip on timing light will also allow you to rule out the ignition system as a cause.

when you changed the fuel lines, did you inspect the fuel tank pickup tubes?

Have you inspected the fuel tanks for any accumulation of debris?

Its possible you are getting fuel starvation due to crud in the tanks...(one bad <contaminated> batch is all it takes). They way this usually happens is startup and idling, in the slip (or in calm water) and the engine runs for hours. Take is out in a chop and depending, in the variables, may 30-90 minutes and the engine bogs or stalls...sometimes over a period of several minutes, sometimes in 10s of seconds... let it sit and things appear normal again...

What is happening is the crud in the tank get stirred up with enough hull motion...depending upon the engine RPM (fuel draw needed) this crud collects on the screen at the bottom of the pickup tube...which reduces the fuel flow which eventually kills the engine. when the hull comes to a rest, the crud drops off the screen and all "evidence" of the restriction disappears...the vacuum gauge on the suction side of the fuel pump is the definitive indicator for this condition...
 
makomark said:
I don't believe the ECU will have any indications that your harness is connected...it just turns the fuel pump on and off and never verifies the fuel pump state (this changes as things mature, to a certain extent). The harness test, as I understand you decription, will eliminate the ECU control of the relay and the relay's contacts...would be good data to have given where you are in the debug process...

I think you will have to monitor the fuel pressure and hopefully have the event occur at the same time...This will help to identify the stalling as a fuel issue and not a spark issue... having a clip on timing light will also allow you to rule out the ignition system as a cause.

when you changed the fuel lines, did you inspect the fuel tank pickup tubes?

Have you inspected the fuel tanks for any accumulation of debris?

Its possible you are getting fuel starvation due to crud in the tanks...(one bad <contaminated> batch is all it takes). They way this usually happens is startup and idling, in the slip (or in calm water) and the engine runs for hours. Take is out in a chop and depending, in the variables, may 30-90 minutes and the engine bogs or stalls...sometimes over a period of several minutes, sometimes in 10s of seconds... let it sit and things appear normal again...

What is happening is the crud in the tank get stirred up with enough hull motion...depending upon the engine RPM (fuel draw needed) this crud collects on the screen at the bottom of the pickup tube...which reduces the fuel flow which eventually kills the engine. when the hull comes to a rest, the crud drops off the screen and all "evidence" of the restriction disappears...the vacuum gauge on the suction side of the fuel pump is the definitive indicator for this condition...
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The Starboard tank we have limited access to the top (Port tank is buried so we based condition as the same as Starboard) and overall we did not see any debris other than a little water which I would except. At about 1/4 tank of gas (160 gallon capacity each), the pickup tube for what we could see is in good condition. I change the filters several times through the season to be safe and cut them open. I found acceptable water (very little, nothing earth shattering) and surprising never see debris. I only purchase gas from our marina. No other boaters are having any gas related problems. I'm looking into installing the vacuum gauge as you suggested. The fuel lines from the pump to the throttle bodies do have a test valve for pressure test gauge is were I get my readings. The timing light I have done before but I agree with you a good idea. When underway these engines are fantastic from idle though any RPM. Throttle response is excellent. I can idle for hours or on-plane without any odd sounds though the exhaust or RPM deviations. But just don't shut them off and expect them to restart 10 minutes late! That's totally crazy and driving me nuts!
 
Captainfredsr said:
The Starboard tank we have limited access to the top (Port tank is buried so we based condition as the same as Starboard) and overall we did not see any debris other than a little water which I would except. At about 1/4 tank of gas (160 gallon capacity each), the pickup tube for what we could see is in good condition. I change the filters several times through the season to be safe and cut them open. I found acceptable water (very little, nothing earth shattering) and surprising never see debris. I only purchase gas from our marina. No other boaters are having any gas related problems. I'm looking into installing the vacuum gauge as you suggested. The fuel lines from the pump to the throttle bodies do have a test valve for pressure test gauge is were I get my readings. The timing light I have done before but I agree with you a good idea. When underway these engines are fantastic from idle though any RPM. Throttle response is excellent. I can idle for hours or on-plane without any odd sounds though the exhaust or RPM deviations. But just don't shut them off and expect them to restart 10 minutes late! That's totally crazy and driving me nuts!
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Finally got the sea-trial (90 minutes) run and test done and back to the slip and ether engine would start. No CEL on ether engine and installed the "Timing Light" and spark was great. I had installed my pressure test gauge which has a "push button" pressure relief valve" I had no gas and very low pressure when opened, but did get some air. The test port is on the high pressure steel line between the filter to the back of the T.B. Keep in mind all O-rings have been replaced several times using the Crusader part numbers to insure correct sizes and no leaks. One T.B. was rebuilt. Can this be "Vapor Lock" ? Once I cycle the pump and clear the air from the system, they start and stay running. if I shut-down and wait for 10-15 minutes, they are hard-starting. Reminding you all steel lines and gas pump have been covered with "Heat-Wrap". These are the temperatures I recorded 1 1/2 hour after "No start" (I had family on board so I had to wait for them to leave) as follows, Exhaust manifolds: 140, Risers: 130, front coolant housing on intake manifold: 150, T.B: 135, gas pump: 120, gas supply hose: 120 near filter, gas filter: 116, E.C.U. : 130. Note when running at any RPM temperature reading are normal. The saga continues!
 
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ok so the TBI unit is not getting fuel after a sustained run...

That means the issue lives somewhere between the fuel tank and the fuel pump.

I would suggest its time for the vacuum gauge to be connected to the suction side of the fuel pump....I think its the fastest way to determine what to do next...
 
Captainfredsr said:
Finally got a long run and test done. No CEL on ether engine. I installed my presser test gauge which has a "push button" pressure relief valve" I had no gas and very low pressure when cracked, but did get some air in the high pressure steel line between the filter to the back of the T.B. Keep in mind all O-rings have been replaced several times and no leaks. One T.B. was rebuilt. Can this be "Vapor Lock" ? Once I cycle the pump and clear the air from the system, they start and stay running. Reminding you all steel lines have been covered with "Heat-Wrap". The saga continues!
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Where is the fuel pump or pumps? For fuel injection, at least one should be in the tank and if that's the case, you should never have vapor lock.

The air could be from the hose on the gauge- it doesn't remain filled after testing.

Look at the ECT (Engine Coolant Temperature) in Diacom- sitting after running causes heat soak and the temperature will naturally be higher than when it runs, even in a car. As long as the temperature doesn't go too high, it should start and run normally but if the ECT sender is bad and the resistance is too high, the ECM reacts by delivering too much fuel and when the engine is already hot, it won't want to start. Open the throttle a bit and see if it starts- if it does, replace the ECT on the engine designated as 'Master'.

You should see fuel pressure when you turn the key(s) to ON without cranking, as the prime cycle. It should then stop after a few seconds- USCG requires that fuel pumps stop when the engine isn't running.
 
makomark said:
Some installations also have a shrader valve on the line from the second filter to the TBI unit...
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No CEL, (we believe problem is not electrical ), gas pumps are mounted on a bracket on the front face of the cylinder head, filter is on the side of head in front and close to the exhaust manifolds, and location is at about half tank level. not in tank. ECT sensors replaced and with no improvement. When engines are " start and stall" condition, at the expected temperature, I get vapor through the Schrader valve, no gas. When ignition is turned "off and on" to cycle (confirmed pump operational) the pump with Schrader open I will finally get gas. Closed Schrader and the engines will start and stay idling. We are thinking of remote mounting on a bracket, the primary filter, pump, secondary filter towards the back of the tank and low on the stringers. Then running the pressure line direct to the T.B. thinking of cooling everything off. Also considering just trying to go to carburetors and appropriate fuel pump, no return. Would the ECU still operate the ignition, anti-knock, fuel pump, and get full RPM? ( I know I will get errors) Another very pricey option would be to go to the Holley four barrel, self contained injection T.B.( yep not worth!) It seems this version of injection may not like the current marine gas mixture. (Yes gas has been checked) Federal EPA continues to mess with redeveloping the gas. I'm the only boat at the marina with these engine systems. Most are carbureted (and no reported starting issues) diesel or newer outboards. Comments please! Thanks!
 
Did you check the suction line with a vacuum gauge yet???

Vapor lock usually doesn't occur in a running engine...it's almost always cheaper to debug a subsystem then to embark on a wholesale replacement..
 
Captainfredsr said:
No CEL, (we believe problem is not electrical ), gas pumps are mounted on a bracket on the front face of the cylinder head, filter is on the side of head in front and close to the exhaust manifolds, and location is at about half tank level. not in tank. ECT sensors replaced and with no improvement. When engines are " start and stall" condition, at the expected temperature, I get vapor through the Schrader valve, no gas. When ignition is turned "off and on" to cycle (confirmed pump operational) the pump with Schrader open I will finally get gas. Closed Schrader and the engines will start and stay idling. We are thinking of remote mounting on a bracket, the primary filter, pump, secondary filter towards the back of the tank and low on the stringers. Then running the pressure line direct to the T.B. thinking of cooling everything off. Also considering just trying to go to carburetors and appropriate fuel pump, no return. Would the ECU still operate the ignition, anti-knock, fuel pump, and get full RPM? ( I know I will get errors) Another very pricey option would be to go to the Holley four barrel, self contained injection T.B.( yep not worth!) It seems this version of injection may not like the current marine gas mixture. (Yes gas has been checked) Federal EPA continues to mess with redeveloping the gas. I'm the only boat at the marina with these engine systems. Most are carbureted (and no reported starting issues) diesel or newer outboards. Comments please! Thanks!
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If everyone elses' engines run fine, I'm nt sure how you reacjed the conclusion that the EPA is at fault. While it's true that Ethanol causes problems, what you have described doesn't sound typical.

No, keeping the ECM and using carburetor won't work- find the root cause and be done with it. EVERYTHING can be tested.
 
jimn said:
If everyone elses' engines run fine, I'm nt sure how you reacjed the conclusion that the EPA is at fault. While it's true that Ethanol causes problems, what you have described doesn't sound typical.

No, keeping the ECM and using carburetor won't work- find the root cause and be done with it. EVERYTHING can be tested.
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Thank you for your help, that eliminates some of my potential alternatives or causes. Will go ahead and revisit the vacuum gauge. I may have to move the filter and bracket from its location to get access for the gauge without disturbing any fuel lines.
 
I've been on a weather delay for testing. My filters were cut open and are clean, no signs of debris or water. Gas color is more "amber" than clear which I assume is the additives that "Valve-Tect" marine gas uses. The question then, could the additive too high of concentration causing boiling and possible the cause of my vapor in the feed lines that have the test port. (I know its stretch) Remember when the engines are hot and I open the valve by hand, no gas. some vapor. Cycling the pump several times with it open will produce gas and the engines start and stay running as if nothing is wrong.
 
I doubt the additive concentration is a candidate but it was never quantified so hard to say...

if there is a consistent void in the fuel line, the question is where is the leak that is inducing the void? Maybe some of the custom plumbing needs to be rechecked?
 
makomark said:
I doubt the additive concentration is a candidate but it was never quantified so hard to say...

if there is a consistent void in the fuel line, the question is where is the leak that is inducing the void? Maybe some of the custom plumbing needs to be rechecked?
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We've been at this problem for several years and just can't find a system problem after exhausting every possibility including switching the tanks with crossover lines. We are curranty designing and relocating a new fuel delivery system with the appropriate marine approved lines utilizing the current pump style and new filter bases (of which one has already been replaced on the port engine) and filters to go more directly to the T.B. Don't think we have any other choose.
 
Update, vacuum gauge installed and no reading at anytime or "no idle on hot shutdown". Trip on the bay ran engines up to 3820 RPM at 18.3 knots for 10 minutes without hesitation, slow down to idle back to slip for 12 minutes. Total run 1:45 minutes, Engines performance are great. Once at slip, both engines restarted normally twice before 10 minutes then " no idle at start up", takes approximately 4-5 hours shut down before restart is normal. Still have no gas at test port, low to no pressure at hot "crank to start", (pump is cycling by placing a finger on it). Keep in mind port engine has check valve in both feed line and return line. Tried removing "dual inlet Crusader fuel pump" to "single inlet" with same specs. Return line directly back to tank from T.B.. But use of this system didn't help. Sounds as if we are at a dead end. Relocating the pump and filters seems to be our only other option. Totally out of ideas after over two seasons with running / testing for this problem.
 
the check valve in the feed line you mentioned is an add on, in addition to the anti-syphon valve? if yes, any idea what its cracking pressure is? same one in the return?

to me, no reading on the vacuum gauge, assuming its plumbed into the suction line before the fuel pump, suggests its not corrected properly...I've never seen one that didn't deflect with the engine running...that's not saying it isn't possible.
 
makomark said:
the check valve in the feed line you mentioned is an add on, in addition to the anti-syphon valve? if yes, any idea what its cracking pressure is? same one in the return?

to me, no reading on the vacuum gauge, assuming its plumbed into the suction line before the fuel pump, suggests its not corrected properly...I've never seen one that didn't deflect with the engine running...that's not saying it isn't possible.
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The starboard engine doesn't have anti-syphon, the two check valves were additional but on the port engine they were removed and this side tank has an new anti-syphon valve. I'll recheck the vacuum gauge installation.
 
Captainfredsr said:
The starboard engine doesn't have anti-syphon, the two check valves were additional but on the port engine they were removed and this side tank has an new anti-syphon valve. I'll recheck the vacuum gauge installation.
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I ran the boat 1hour and 45 minutes and for 5 minutes at 3820 RPM at 18knotts then slow down to an idle for several minutes without stalling (which they have never done), so if there is a fuel restriction when hot, why are the engines still running which drives me crazy?!
 
The pump always has a restriction when its running as it has to draw the fuel from the tank...I think in your case it isn't huge which is a good thing. the thought with the vacuum gauge was to get an idea what "normal" is being as you have a custom (non-standard) fuel delivery setup.

Have you ever scanned the throttle bodies with an IR gun since the issue started? some engine rooms are good at dissipating heat while others are great at retaining it...
 
makomark said:
The pump always has a restriction when its running as it has to draw the fuel from the tank...I think in your case it isn't huge which is a good thing. the thought with the vacuum gauge was to get an idea what "normal" is being as you have a custom (non-standard) fuel delivery setup.

Have you ever scanned the throttle bodies with an IR gun since the issue started? some engine rooms are good at dissipating heat while others are great at retaining it...
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Might not be a bad idea to use a timing light on the injectors, to watch the spray pattern. If there's any 'tearing' or if it's not delivering much fuel, it will be visible while cranking or running.
 
To answer, spray pattern seems good. I have been questioning the quality of the gas causing my engine staring issues. Finally had a chance to do a visual comparison. Information on what I see as follows: Note in December 2024 I put approximately 70 gallons in each tank gas ( tanks are 173 gallon capacity and no crossover} that gave me just over 3/4 level in each tank three days before pulling for the winter. Currently I purchased a gallon of gas in a gas-container ( ValvTect, brand ) from my marina as normal. Its extremely clear. Back on 4/10/2025 replaced primary filters and the gas has a slightly amber tint and the media was clean, no water dropout. On 6/14/2025 changed both filters again, this gas is slightly darker amber tint (but almost the same) and again the media is clean and no water dropout. Unfortunately not sure which tank since I have samples from both sides. Both engines continue to have the same continuing problem when at normal engine temperature, will start but will not stay running after sea tail for about 45 minutes to an hour. Cold starts are fine, no problem. I've been running the boat around the area to drawn down as much of the tank gas a possible before adding new. Could this tint be to much additive causing my hot start issue? (vapor in the high pressure lines at the TB's) Will be pursuing this gas samples with the marina owners shorty. What do you think?
 
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