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94 gmc 6.5 turbo deisel sputtering
- Thread starter Boblaw66
- Start date
dbrannon79
I'm getting there!
I would think you have air getting into the fuel system. replace your return line on the IP which is a 1/4" hose about 6" in length located right in the front of the IP up top. replace it with some clear tubing you can get at most any hardware store. id does not need to be fuel rated, run the engine and see if you don't see air bubbles fuel flowing.
jrsavoie
Recruit
1994 needs the lift pump relay upgrade.
If you make your own, make it plug and play, like leroy does
Install a fuel pressure gauge
If you make your own, make it plug and play, like leroy does
Install a fuel pressure gauge
Okay I'll try that. Thanx
Where should I go to buy a lift pump? Prices r all over the place for ac delco. Thanx
dbrannon79
I'm getting there!
if you plan to go factory OEM style part, use the ac delco EP-158. it's the better of the ones available. I have this installed on mine, but there are modifications needed to connect the lines.
There are many other aftermarket and much better options out there like the Air Dog, but it's a buy once cry once kinda thing.
There are many other aftermarket and much better options out there like the Air Dog, but it's a buy once cry once kinda thing.
As an Amazon Associate we earn from qualifying purchases.
DieselAmateur
She ain't revved 'til the rods are thrown...
black smoke means unburned fuel. Check your air filter, intake and turbo. Does the compressor wheel spin freely? As already suggested the clear tubing on the return line is the cheapest way to see if you have air intrusion or not.
I see new fuel tank, was that also a new sending unit? The tank sock that comes on a new sending unit is the wrong type. That could be part of your fuel starvation. Delete the sock and use a simple inline mesh filter like NAPA #3270. just cut the steel lines with a small pipe cutter pre lift pump and splice in using rubber hose and clamps.
Well documented that the factory lift pump is anemic. If you don't want to upgrade I've always wondered what results would be in running two factory pumps in parallel, teed off the sending unit and teed together back at the FFM.
Also where is the IP from? Likely not the culprit but with issues after new parts installed everything is suspect
I see new fuel tank, was that also a new sending unit? The tank sock that comes on a new sending unit is the wrong type. That could be part of your fuel starvation. Delete the sock and use a simple inline mesh filter like NAPA #3270. just cut the steel lines with a small pipe cutter pre lift pump and splice in using rubber hose and clamps.
Well documented that the factory lift pump is anemic. If you don't want to upgrade I've always wondered what results would be in running two factory pumps in parallel, teed off the sending unit and teed together back at the FFM.
Also where is the IP from? Likely not the culprit but with issues after new parts installed everything is suspect
Stanadyne I think for the ip. Don't forget I'm a contractor, not a mechanic, lol. All that sounds goods but I don't know how to do all that. I'm gonna do the clear line and change lift pump for now. I want a good lift pump, ac delco from where? I read a while back someone used a marine lift pump.
dbrannon79
I'm getting there!
If your are ok with buying online here are a couple of links.
keep in mind with amazon, they do not honor the full warranty period but supposedly you can get that direct from AC Delco by this seller only, I have not confirmed this. Now Summit Racing on the other hand will honor warranties without issues.
www.summitracing.com
Like DieselAmateur said, and it 100% correct. if you had the sending unit replaced inside the new tank, that could be the source of your issue, this will also burn up the LP fast which in turn will fubar your new IP as well.
it's not hard to drop the tank or pull and lift the pickup bed to get at the sending unit. your a contractor so you could easily once the screen filter sock is removed from the sending unit inside the tank, use a tubing cutter on the supply steel line, use a flaring tool same as what is used for copper water pipe and put a small bubble flare on the cut ends of the steel lines. and install an inline fuel filter with rubber hose and clamps.
just keep in mind that with the inline filter, it needs to be changed often. I would vote to replace it at each oil change. it's cheap insurance as well as keeping a spare LP in the tool box for when disaster strikes.
spare parts you say.... things to keep in your rig at all times... belt, lift fuel pump, PMD if your rig has an electronic IP. also if it's an electronic IP, get you an PMD relocation kit and mount that thing out in the hole on the front bumper away from the engine heat where it can get fresh air on the heatskink fins. we can all help you with this. these things will help make your rig more reliable for the long haul.
BTW, easy way to tell if it's electronic is to look at the IP and see if you have actual throttle cables running from the go pedal in the cab to the IP. if you don't, then it's "drive by wire" fully electronic. in 1994, it could be ether one.
keep in mind with amazon, they do not honor the full warranty period but supposedly you can get that direct from AC Delco by this seller only, I have not confirmed this. Now Summit Racing on the other hand will honor warranties without issues.
ACDelco 25115224 ACDelco Electric External Fuel Pumps | Summit Racing
Free Shipping - ACDelco Electric External Fuel Pumps with qualifying orders of $109. Shop Fuel Pumps at Summit Racing.
Like DieselAmateur said, and it 100% correct. if you had the sending unit replaced inside the new tank, that could be the source of your issue, this will also burn up the LP fast which in turn will fubar your new IP as well.
it's not hard to drop the tank or pull and lift the pickup bed to get at the sending unit. your a contractor so you could easily once the screen filter sock is removed from the sending unit inside the tank, use a tubing cutter on the supply steel line, use a flaring tool same as what is used for copper water pipe and put a small bubble flare on the cut ends of the steel lines. and install an inline fuel filter with rubber hose and clamps.
just keep in mind that with the inline filter, it needs to be changed often. I would vote to replace it at each oil change. it's cheap insurance as well as keeping a spare LP in the tool box for when disaster strikes.
spare parts you say.... things to keep in your rig at all times... belt, lift fuel pump, PMD if your rig has an electronic IP. also if it's an electronic IP, get you an PMD relocation kit and mount that thing out in the hole on the front bumper away from the engine heat where it can get fresh air on the heatskink fins. we can all help you with this. these things will help make your rig more reliable for the long haul.
BTW, easy way to tell if it's electronic is to look at the IP and see if you have actual throttle cables running from the go pedal in the cab to the IP. if you don't, then it's "drive by wire" fully electronic. in 1994, it could be ether one.
As an Amazon Associate we earn from qualifying purchases.
Thanx for that. I'm sure they didn't replace the sending unit. I have a 12ft stake body dump so access is easy. After we did everything maybe 8 mos or so ago it ran great then just started that sputtering. I put it under load today, no sputtering, even up hills but some black smoke.
MrMarty51
Well-Known Member
Whats the boost pressure running at ? ? ? ?
Vacuum pump, if so equipped, check the vacuum on the suction side of the pump.
IDR how many inches of vacuum that the pump should be drawing, depending on altitude but I’m guessing at least 22 to 25 inches of vacuum.
Black smoke from my truck was due to a bad vacuum pump.
Vacuum pump, if so equipped, check the vacuum on the suction side of the pump.
IDR how many inches of vacuum that the pump should be drawing, depending on altitude but I’m guessing at least 22 to 25 inches of vacuum.
Black smoke from my truck was due to a bad vacuum pump.
dbrannon79
I'm getting there!
Be sure to get the clear tubing installed on the IP return too. I would do this before trying to pull apart anything fuel related or installing filters. also if you engine is fully electronic, (no real throttle cables to the IP) you will have a vacuum operated waste gate on the turbo, there will be a vacuum pot with a rod to a lever on the side of the turbo. with the engine idling, you should not be able to actuate the rod back n fourth by hand, if you can move it by hand, you issue is boost pressure as in a vacuum hose is leaking or the vacuum pump located under the AC compressor on the passenger side has 
the bed!
the bed!
dbrannon79
I'm getting there!
the vacuum hose should run from the pot on the turbo over to a small solenoid located on top of the drivers side valve cover, then from there direct to the vacuum pump. if you have an EGR then there will be two of those solenoids, one for the turbo and one for the EGR. trace those hoses to make sure they aren't cracked. GM used hard plastic tubing which easily cracks and causes vacuum leaks
you can disconnect the hose at the turbo with it running and put your finger over the end to feel for a good amount of vacuum too.
you can disconnect the hose at the turbo with it running and put your finger over the end to feel for a good amount of vacuum too.
dbrannon79
I'm getting there!
the bubble fare I mentioned is simply to give something for the rubber fuel hose grip when you slip it over the line and clamp it. this way it won't push off the steel line under pressure. the LP should only be pushing 8-14 PSI up to the IP.. the steel lines from the IP to the each of the injectors will reach up over 2000 psi. so use safety there!
dbrannon79
I'm getting there!
Yup, but that's only on the short steel lines coming off the IP going to each injector. that's low pressure compared to the newer diesels that produce upwards around 20k to 30k PSI !