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Crusader throttle body fuel injection

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infinityron

Contributing Member
I am helping a friend with possible purchase of a 1998 Silverton with Crusader 454 XL s and throttle body fuel injection. Already had a mechanical survey done and outcome was very good. I am a little unfamiliar with throttle body fuel injection though. What are pros and cons? Also, can someone recommend a scan tool to carry aboard that does not need to be pricey but good enough to do basic troubleshooting if need arises?
 
I'd say the biggest drawback is they had a short production run and many factory parts are NLA....that said, there is decent aftermarket support. when they work, they are decent performers...
They have the early (very simple) ECUs...the 'flasher' is typically adequate for debugging...as long as you have the (GM) factory manual content available.
there have been a few threads in the Crusader section on the TBIs, over the years...
 
makomark said:
I'd say the biggest drawback is they had a short production run and many factory parts are NLA....that said, there is decent aftermarket support. when they work, they are decent performers... They have the early (very simple) ECUs...the 'flasher' is typically adequate for debugging...as long as you have the (GM) factory manual content available. there have been a few threads in the Crusader section on the TBIs, over the years...
Click to expand...
Mark, no one else is chiming in here, but let me ask your opinion in different terms....this potential purchase vessel has received a thorough mechanical survey with good results. Engines only have 350 hours. Start right up. Great compresssion all around both engines (130-140). Oil sample results good. The mechanic doing the survey mentioned that the TBI systems weak link was "idle air control valve" and "throttle position sensor". I looked up and see that Sierra has readily available aftermarkets on these parts and they look like easy replacement items. So, my thinking is stash two of each of these things on board and at the ready. There was a facebook comment about most people with TBI converting to carbs when they go out due to lack of availability of ECU's. What do you think? I'm inclined to advise proceed with purchase based on the overall good condition of engines. What about the ECU issue, and I'd still like to know what kind of scan tool to recommend for self service.
 
I'm not a fan of Sierra in recent years....I think one of each, adequately stored, would be adequate until an issue arises. I'm sure you'd be better off with Delco parts if you can find them. The only PITA operation I remember (been a while since i worked a GM TBI engine) was the fuel pressure check...the TBI doesn't have an integral schrader valve so you can buy or make an adapter...i also recall a couple changes in the fuel pressure spec for their short production run.

On ECU's they rarely fail. If there is a major issue, there are many 'repair shops' that can provide viable units.

On the scanners, Rinda products are the industries gold standard and provide the most flexibility. for basic troubleshooting, you can use the simple diode, resistor, and jumper like was used on a mid-80s GM car...the only difference is the marine version of the OBD connector is different. There are a few articles on the WWW and a search engine with some time will locate them. I think there are a couple of OBDII scanner makers that now cover marine products as well - last time I looked, you can even buy (relatively cheap) tuning software for the MEFI units...
 
infinityron said:
Mark, no one else is chiming in here, but let me ask your opinion in different terms....this potential purchase vessel has received a thorough mechanical survey with good results. Engines only have 350 hours. Start right up. Great compresssion all around both engines (130-140). Oil sample results good. The mechanic doing the survey mentioned that the TBI systems weak link was "idle air control valve" and "throttle position sensor". I looked up and see that Sierra has readily available aftermarkets on these parts and they look like easy replacement items. So, my thinking is stash two of each of these things on board and at the ready. There was a facebook comment about most people with TBI converting to carbs when they go out due to lack of availability of ECU's. What do you think? I'm inclined to advise proceed with purchase based on the overall good condition of engines. What about the ECU issue, and I'd still like to know what kind of scan tool to recommend for self service.
Click to expand...

I can say for certain that the IAC and TPS is nothing more than a GM TBI sensor. I have installed both, both worked perfectly, and neither has been an issue. The same is true for the coolant temp sensor.

The MAP sensor may be a different story, (I have not confirmed that the auto MAP and marine MAP are the same, but they appear to be) and the biggest bitch in trouble shooting these engines, is dealing with the multi-PSI systems (the early systems are 9-10 PSI "low PSI" systems, the 96-later are "high PSI 14ish PSI systems, and discerning parts is a nightmare.).
 
I wasn't sure if I should start a new thread but I am posting here because of the thread title. It doesn't make sense to have multiple threads with the same heading. I have a pair of 1994 Crusader 454 XL TBI engines. They were re-manned in 2023 and have 80 and 75 hours respectively. Other than a few electronic issues replacing some of the sensors, they run fine. I just changed oil for the third time (the first two were at 10 and 25 hours in accordance with the shop recommendations.) and have had oil tested after each change. The latest report indicates 2.8 percent fuel in the sample which the lab thinks is high but may be due to low hours and to pull another sample in 20 or so hours. I strictly followed factory break-in guidance changing throttle settings every 5-15 minutes with WOT 2 minutes max. After the firest 25 hours, when they were supposed to be broken in, the great majority of the hours have been at 2200-2500 RPMs. As to source of the fuel, my mechanic seems to think its coming by the rings due to rings may not being fully seated, which makes sense. The lab says its the injectors or fuel pump (how would they get fuel into the oil system?) We added 16 oz of ZDDP zinc with first two oil changes. Assuming the rings are not fully seated (I sure don't want to tear down the engine to find out!) Should we keep that much zinc in the system and run the engines harder. I'm running Rotella 15w40T4 which their info says contains 1050 parts per million and i added 3 oz. per engine this last oil change to bring up to 1400 ppm that seems to be the consus for the correct amount for these big blocs with flat tappet cams. My questions are:
1. Assuming the rings have not fully seated, what measures should i take? Add more zinc? Increase RPMs?
2. If i replace TBI injectors, will automotive injectors do? Are they standard e.g. Chevy Suburban 2500 454 available at NAPA or AutoZone? Probably should have spares on board anyway, as was mentioned above (2 years ago !!)
3. What test should be run on the fuel pumps? We don't understand how a faulty pump could push fuel into the oil. We had a fuel pump issue early on just after the re-power which I posted about. It concerned the return port on the electric pump going back into the throttle body rather than to the fuel tank. We closed off the second return and re-directed the fuel back to the fuel tank.
I'll appreciate any thoughts and help.
 
CaptJoe3 said:
... My questions are:
1. Assuming the rings have not fully seated, what measures should i take? Add more zinc? Increase RPMs?
2. If i replace TBI injectors, will automotive injectors do? Are they standard e.g. Chevy Suburban 2500 454 available at NAPA or AutoZone? Probably should have spares on board anyway, as was mentioned above (2 years ago !!)
3. What test should be run on the fuel pumps? We don't understand how a faulty pump could push fuel into the oil. We had a fuel pump issue early on just after the re-power which I posted about. It concerned the return port on the electric pump going back into the throttle body rather than to the fuel tank. We closed off the second return and re-directed the fuel back to the fuel tank....
Click to expand...
Who did the 'reman' and how extensive was it; complete engine/short block/long block??

I would think a leak down test would give insight into the condition of the cylinders... At 75 hours, I'd think the engine has achieved full break in. As far as oil and additives, the reman source really has the gavel - they know what went into the engine and what should be done to satify any warranty.

I don't believe you need any more ZDDP that what is in the Rotella oil. We rung up over 3000 hours on a set of 454's before overhaul and the machinist said everything was still good in the bottom end.

On the injectors, there have been a couple of threads here covering the TBI units...using the search funtion should find some part numbers...They were standard GM products but had some updates during their short production span.

On the fuel pumps, the comment could have been rooted in the old (carb based) mechanical pumps - their sight tubes dump leaking fuel from the fuel pump into the carb's primary bore...never seen that kind of setup on the electric pumps with the TBI's.

2.8 % fuel in the oil appears high to me...assuming it is unburnt (raw) fuel? my gut says the injectors are the most likely source (and the balance of the TBI unit is the remainder). The injectors can be tested for leaks...many times they respond well to ultrasonic cleanings.
 
CaptJoe3 said:
I wasn't sure if I should start a new thread but I am posting here because of the thread title. It doesn't make sense to have multiple threads with the same heading. I have a pair of 1994 Crusader 454 XL TBI engines. They were re-manned in 2023 and have 80 and 75 hours respectively. Other than a few electronic issues replacing some of the sensors, they run fine. I just changed oil for the third time (the first two were at 10 and 25 hours in accordance with the shop recommendations.) and have had oil tested after each change. The latest report indicates 2.8 percent fuel in the sample which the lab thinks is high but may be due to low hours and to pull another sample in 20 or so hours. I strictly followed factory break-in guidance changing throttle settings every 5-15 minutes with WOT 2 minutes max. After the firest 25 hours, when they were supposed to be broken in, the great majority of the hours have been at 2200-2500 RPMs. As to source of the fuel, my mechanic seems to think its coming by the rings due to rings may not being fully seated, which makes sense. The lab says its the injectors or fuel pump (how would they get fuel into the oil system?) We added 16 oz of ZDDP zinc with first two oil changes. Assuming the rings are not fully seated (I sure don't want to tear down the engine to find out!) Should we keep that much zinc in the system and run the engines harder. I'm running Rotella 15w40T4 which their info says contains 1050 parts per million and i added 3 oz. per engine this last oil change to bring up to 1400 ppm that seems to be the consus for the correct amount for these big blocs with flat tappet cams. My questions are:
1. Assuming the rings have not fully seated, what measures should i take? Add more zinc? Increase RPMs?
2. If i replace TBI injectors, will automotive injectors do? Are they standard e.g. Chevy Suburban 2500 454 available at NAPA or AutoZone? Probably should have spares on board anyway, as was mentioned above (2 years ago !!)
3. What test should be run on the fuel pumps? We don't understand how a faulty pump could push fuel into the oil. We had a fuel pump issue early on just after the re-power which I posted about. It concerned the return port on the electric pump going back into the throttle body rather than to the fuel tank. We closed off the second return and re-directed the fuel back to the fuel tank.
I'll appreciate any thoughts and help.
Click to expand...

FWIW, adding more zinc won't help the rings to seat. Oil should never really be outside of the crankcase/oil system. The cylinders are relatively dry, or should be.

High fuel in the oil is much more likely a sign of running rich, would help prevent the rings from properly seating. Rich conditions in those TBI engines are caused from one of two things:

1) bad injectors
2) faulty manifold temp sensor

Make sure both are good, both are capable of washing out your rings and blowing a brand new engine, and it wouldn't be covered under warranty.
 
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