Nothing left to check? VP 5.7GSI wont start - good fuel pressure, good ecm, wiring
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Cam timing though? Should I be wasting my money and time checking it? Or would it be backfiring and sneezing with cam timing off a tooth? Once you get this thing started she idles super smooth.
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He's got 30psi. So the reg must be working.
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Walker Products 5002016 - listed as compatible with GM trucks 7.4l 1987 - 1994. It's the only auto application I can find it for, but Rock Auto has it listed for my engine model, and a few other models (4.3's).
The second Walker injector is 5001136. This one is a marine specific injector, found in walkers marine catalog. This one is listed under 2000 Volvo Penta 5.7 on rock auto, and on the walker marine catalog as a bunch of 4.3's, and 1994-2007 volvo 5.7's.
The first one seems logical, based on its displacement application, and time period. The second sounds promising that it's designated as a marine injector and is possibly rated at 30 psi. The question is, are they available.
The second Walker injector is 5001136. This one is a marine specific injector, found in walkers marine catalog. This one is listed under 2000 Volvo Penta 5.7 on rock auto, and on the walker marine catalog as a bunch of 4.3's, and 1994-2007 volvo 5.7's.
The first one seems logical, based on its displacement application, and time period. The second sounds promising that it's designated as a marine injector and is possibly rated at 30 psi. The question is, are they available.
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2nd one sounds more pomising...I said sounds.
The 87-93 truck 7.4L injectors ae the 75-85 lb/hr at 13psi, Neve used at higher psi's. The 94-95 7.4L trucks had the 30psi fuel system with a different injector...which sounds like MErc used in there TBI's and in which I wonder if are the same Volvo used but with diffeent stamping #.
The 87-93 truck 7.4L injectors ae the 75-85 lb/hr at 13psi, Neve used at higher psi's. The 94-95 7.4L trucks had the 30psi fuel system with a different injector...which sounds like MErc used in there TBI's and in which I wonder if are the same Volvo used but with diffeent stamping #.
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2nd one sounds more pomising...I said sounds.
The 87-93 truck 7.4L injectors ae the 75-85 lb/hr at 13psi, Neve used at higher psi's. The 94-95 7.4L trucks had the 30psi fuel system with a different injector...which sounds like MErc used in there TBI's and in which I wonder if are the same Volvo used but with diffeent stamping #.
The 87-93 truck 7.4L injectors ae the 75-85 lb/hr at 13psi, Neve used at higher psi's. The 94-95 7.4L trucks had the 30psi fuel system with a different injector...which sounds like MErc used in there TBI's and in which I wonder if are the same Volvo used but with diffeent stamping #.
What is the availability of the 30 psi truck injectors?
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Hello all. I have a 2000 VP 5.7GSI TBI injected motor which had an oil pan issue last fall. The engine ran great all year, but I pulled the motor to do an oil pan over the winter. Along with the oil pan I replaced a few other items, had the valves lapped, stem seals replaces, replaced the oil pump, injectors rebuilt, and I rebuilt the TBI.
4 weeks ago I dropped the engine back in, buttoned everything up, and she wouldn't start. I went through the normal tests. First verified that I had spark, which I do. Second I verified that the injectors were spraying, which they were. Third I verified compression - 175 PSI Max at all cylinders, 90 PSI first bump. At this point I decided to pour a little fuel in the intake to see if the problem was fuel related. The engine fired up immediately, ran for 3-5 seconds until it started starving for fuel and slowly cut out.
Knowing this must be a fuel problem, I did the following items: BTW - I have a native MEFI III motor, but with a MEFI IV computer and conversion harness, since it died three years ago in the previous owners hands.
1. Verified fuel pressure - 6PSI low pressure pump, 30 PSI high pressure, measured at the TBI.
2. Verified fuel volume just in case - will fill up a coffee can in 2 seconds.
3. Sent my injectors BACK out to an independent shop to be flow tested again, just to be sure the first place didn't make a mistake. They checked out fine.
4. Rebuilt the TBI AGAIN, just to make sure I didn't tear the diaphragm the first time. I don't think I would get a proper fuel pressure reading without a working diaphragm, but just to be sure I did.
Nothing changed at this stage, so then I figured my problem was electrical.
I pulled the codes, and I had a myriad of them, but all were due to me cranking with items such as the MAP or TPS disconnected trying to override a faulty sensor if that was causing it not to run. I tried disconnecting the S.L.O.W sensors, and this made no difference.
My marina suggested that even though my injectors were spraying, and pulsing, that I should put a NOID light on it. I did this, and it flashed rapidly. I don't know how bright they typically flash, but mine seemed a bit dim, so then I figured my problem was voltage or ground from the injectors. I checked the following items at this point:
5. Verified that my injectors had B+ voltage at the hot lead (with a multimeter). The battery had 12.58 V, injectors 12.47 V.
6. Traced the injector ground wires back to the J1/J2 connectors and checked for continuity, then traced the same wires through my MEFI IV conversion harness, and also had continuity.
7. Traced and checked all the ignition module wires back to the ECM and checked for continuity.
8. Traced all four MEFI IV ground pins to the ground wire, and checked for continuity.
9. Checked both my engine post grounds for abnormal resistance.
After getting this far, I decided my injector drivers must have died in the ECM. I sent my ECM to OBD Diagnostics to be bench tested. He called me two days later and said the unit was fine.
After getting my ECM back, I replaced the ignition module, and coil - not sure why, but somebody at my marina suggested I do this since he had a similar problem and it turned out to be these. No change in my condition after replacing both.
Now I do not know where else to turn. I apparently have a good ECM, new ignition module and coil, good spark, good compression, good injectors, good fuel pressure, and yet my engine wont start. If I let it sit all night, it usually will sneeze on the first few cranks of the day, but that is all. As it was before, if I pour fuel down the intake, she will start up and run until it starves for fuel. The engine has set codes before, but as I said they will never come back unless I disconnect a sensor or connector, so there are no hard faults.
I am getting a bit desperate at this point, since even my local mechanics are confused. I am considering buying a SBC TBI off a GM truck locally just to try to start my engine, and if it runs then I know my TBI is bad SOMEHOW, even though the injectors have been tested twice, and TBI rebuilt twice. For whats its worth, I don't know what injector post resistance is supposed to be, but mine is 1.5 OHMS.
Should I just by the Diacom tool and start reading sensors? Or should I pull my harness out of the boat, unwrap it and trace every single wire/check it for continuity? I also ordered a new MAP sensor just because I want to rule it out - even though I am told disconnecting it will set the ECM in a default that should allow it to run, and this didn't change my condition.
Any help would be greatly appreciated. If anyone needs a diagram drawn of the MEFI III to IV conversion harness I can do that.
,
4 weeks ago I dropped the engine back in, buttoned everything up, and she wouldn't start. I went through the normal tests. First verified that I had spark, which I do. Second I verified that the injectors were spraying, which they were. Third I verified compression - 175 PSI Max at all cylinders, 90 PSI first bump. At this point I decided to pour a little fuel in the intake to see if the problem was fuel related. The engine fired up immediately, ran for 3-5 seconds until it started starving for fuel and slowly cut out.
Knowing this must be a fuel problem, I did the following items: BTW - I have a native MEFI III motor, but with a MEFI IV computer and conversion harness, since it died three years ago in the previous owners hands.
1. Verified fuel pressure - 6PSI low pressure pump, 30 PSI high pressure, measured at the TBI.
2. Verified fuel volume just in case - will fill up a coffee can in 2 seconds.
3. Sent my injectors BACK out to an independent shop to be flow tested again, just to be sure the first place didn't make a mistake. They checked out fine.
4. Rebuilt the TBI AGAIN, just to make sure I didn't tear the diaphragm the first time. I don't think I would get a proper fuel pressure reading without a working diaphragm, but just to be sure I did.
Nothing changed at this stage, so then I figured my problem was electrical.
I pulled the codes, and I had a myriad of them, but all were due to me cranking with items such as the MAP or TPS disconnected trying to override a faulty sensor if that was causing it not to run. I tried disconnecting the S.L.O.W sensors, and this made no difference.
My marina suggested that even though my injectors were spraying, and pulsing, that I should put a NOID light on it. I did this, and it flashed rapidly. I don't know how bright they typically flash, but mine seemed a bit dim, so then I figured my problem was voltage or ground from the injectors. I checked the following items at this point:
5. Verified that my injectors had B+ voltage at the hot lead (with a multimeter). The battery had 12.58 V, injectors 12.47 V.
6. Traced the injector ground wires back to the J1/J2 connectors and checked for continuity, then traced the same wires through my MEFI IV conversion harness, and also had continuity.
7. Traced and checked all the ignition module wires back to the ECM and checked for continuity.
8. Traced all four MEFI IV ground pins to the ground wire, and checked for continuity.
9. Checked both my engine post grounds for abnormal resistance.
After getting this far, I decided my injector drivers must have died in the ECM. I sent my ECM to OBD Diagnostics to be bench tested. He called me two days later and said the unit was fine.
After getting my ECM back, I replaced the ignition module, and coil - not sure why, but somebody at my marina suggested I do this since he had a similar problem and it turned out to be these. No change in my condition after replacing both.
Now I do not know where else to turn. I apparently have a good ECM, new ignition module and coil, good spark, good compression, good injectors, good fuel pressure, and yet my engine wont start. If I let it sit all night, it usually will sneeze on the first few cranks of the day, but that is all. As it was before, if I pour fuel down the intake, she will start up and run until it starves for fuel. The engine has set codes before, but as I said they will never come back unless I disconnect a sensor or connector, so there are no hard faults.
I am getting a bit desperate at this point, since even my local mechanics are confused. I am considering buying a SBC TBI off a GM truck locally just to try to start my engine, and if it runs then I know my TBI is bad SOMEHOW, even though the injectors have been tested twice, and TBI rebuilt twice. For whats its worth, I don't know what injector post resistance is supposed to be, but mine is 1.5 OHMS.
Should I just by the Diacom tool and start reading sensors? Or should I pull my harness out of the boat, unwrap it and trace every single wire/check it for continuity? I also ordered a new MAP sensor just because I want to rule it out - even though I am told disconnecting it will set the ECM in a default that should allow it to run, and this didn't change my condition.
Any help would be greatly appreciated. If anyone needs a diagram drawn of the MEFI III to IV conversion harness I can do that.
,
Last edited by offshore312; 05-20-2015 at 07:02 AM.
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Just so everyone knows, here is my plan:
1. Source 7.4 L 30 psi truck injextors & Walker marine 5001136 injectors. Before the weekend.
2. Have Rinda diacom here for the weekend. I want to be 100% sure my sensors are communicating properly, and view event logs / spark advance at various rpms.
3. If both 1&2 fail to solve anything, then I'll pull the timing cover off and check that it's lined up properly. If needed I will pull the engine out of the hull again.... Ugh...
I will post a link to the timing gear and chain set I bought.
Edit:
Here is the timing chain set I bought.
http://bpi.ebasicpower.com/p/MEL3-202SA
Is it possible that my cam timing is off one tooth, but the engine will still idle as smooth as it does when started? Once you get this thing running it idles super smooth, and if you maintain a steady RPM it runs smooth a that RPM too. Vacuum readings are good as well, and as SB pointed out, good with an engine that's running like crap which likely means it will improve even more when its fixed.
I am happy to take off the front of the engine to check this weekend though. Hopefully I can get the damn balancer off in the hull.
Edit 2: Ordered the Diacom tool. I wont let this thing win. I want to rule out every single other possibility.
Last edited by nunnink23; 05-20-2015 at 08:58 AM.
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Wait a minute.... I need to pull the engine to pull the timing cover don't I? I have a one piece Fel-Pro oil pan gasket, but how could I get the timing cover back on and sealed correctly without dropping the oil pan?
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He has voltage
He has two new set's of high flow injectors...are they failing???
The pressure reg might hold pressure but is it delivering the injectors are not.
In 94/95 Gm did go to 30lbs on there TBI and they did use a smaller injector i just dont have the resources for the research perhaps the tj17 is the right injector smaller yes but could it handle the 30lbs if so it just a matter of pulse width. So they could be the right injector.Merc uses them merc used mefi now did merc use a 454 tbi on there 5.7.
http://www.summitracing.com/parts/sm...tions/make/gmc
TJ 17 injector there are some matches
Replaces OEM part #•MERCURY MARINE 852956A1
•VOLVO PENTA 3858941
Fits:MerCruiser MCM GM V6 & V8(305 &350) TBI engines........................................... ............................
Fits: Volvo 4.3GXi-A, 4.3GLPWTC, 4.3GLPWTR, 4.3GSPWTC, 4.3GSPWTR, 4.3GIPWTC, 4.3GIPWTR, 4.3GIJWTR, 4.3GSJWTR, 4.3GLPEFS AND 4.3GiPEFS
1996 (4)
1995 (22) ......................................
1994 (21) .....................................
Universal:
No
OEM Stock Replacement:
Yes
Computer and Engine Modifications Required:
No
Make:
GMC
Model:
C2500
Submodel:
SIERRA SL
Beginning Year:
1994
Ending Year:
1995
Engine Type:
V8
Liter:
7.4
CID:
454
Engine Size:
7.4L/454
Engine Family:
Chevy big block Gen V
Fuel Type:
Gasoline
Universal:
No
OEM Stock Replacement:
Yes
Computer and Engine Modifications Required:
No
Make:
GMC
Model:
C2500
Submodel:
SIERRA SLE
Beginning Year:
1994
Ending Year:
1995
Engine Type:
V8
Liter:
7.4
CID:
454
Engine Size:
7.4L/454
Engine Family:
Chevy big block Gen V
Fuel Type:
Gasoline
He has two new set's of high flow injectors...are they failing???
The pressure reg might hold pressure but is it delivering the injectors are not.
In 94/95 Gm did go to 30lbs on there TBI and they did use a smaller injector i just dont have the resources for the research perhaps the tj17 is the right injector smaller yes but could it handle the 30lbs if so it just a matter of pulse width. So they could be the right injector.Merc uses them merc used mefi now did merc use a 454 tbi on there 5.7.
http://www.summitracing.com/parts/sm...tions/make/gmc
TJ 17 injector there are some matches
Replaces OEM part #•MERCURY MARINE 852956A1
•VOLVO PENTA 3858941
Fits:MerCruiser MCM GM V6 & V8(305 &350) TBI engines........................................... ............................
Fits: Volvo 4.3GXi-A, 4.3GLPWTC, 4.3GLPWTR, 4.3GSPWTC, 4.3GSPWTR, 4.3GIPWTC, 4.3GIPWTR, 4.3GIJWTR, 4.3GSJWTR, 4.3GLPEFS AND 4.3GiPEFS
1996 (4)
1995 (22) ......................................
1994 (21) .....................................
Universal:
No
OEM Stock Replacement:
Yes
Computer and Engine Modifications Required:
No
Make:
GMC
Model:
C2500
Submodel:
SIERRA SL
Beginning Year:
1994
Ending Year:
1995
Engine Type:
V8
Liter:
7.4
CID:
454
Engine Size:
7.4L/454
Engine Family:
Chevy big block Gen V
Fuel Type:
Gasoline
Universal:
No
OEM Stock Replacement:
Yes
Computer and Engine Modifications Required:
No
Make:
GMC
Model:
C2500
Submodel:
SIERRA SLE
Beginning Year:
1994
Ending Year:
1995
Engine Type:
V8
Liter:
7.4
CID:
454
Engine Size:
7.4L/454
Engine Family:
Chevy big block Gen V
Fuel Type:
Gasoline
Last edited by Tail_Gunner; 05-20-2015 at 11:46 AM.
#230
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The tbi regulator is after the the injectors.
Therefore measuring the psi in the feed line to the tbi unit will be the same fuel psi the injectors are seeing.
Therefore measuring the psi in the feed line to the tbi unit will be the same fuel psi the injectors are seeing.