hello and need help with new DD/project truck
01-18-2017, 04:18 PM
#1
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hello and need help with new DD/project truck
Firstly, hello everyone, I am new to the forum, and need some help with my truck.
Long story short, I am navy stationed in OK, and traded my d21 for this truck with a friend who was moving to California, as this beast wouldn't pass their emissions, so history on the truck is kind of spotty, here is what i know after a month of driving it:
At some point, it was a 5.8(?) when you run the vin, that is what the build was.
It has 206k miles, and overdrive trans.
In the cold it needs to be started a few times as it would cut off after a minute or so.
anything past half throttle, and the motor would cut out, and then back on at the original rpm (approx, i don't have a tach)
Sunday night, i filled up the rear tank, on my way home (in the rain), the O/D light began flashing, and the transmission started jumping gears, and the engine started jumping revs, before finally shutting off and not starting again. Monday, i started troubleshooting and had no fuel pressure on the rail. So, since i could hear both fuel pumps priming, i replaced the fuel filter, now i have plenty of pressure, but the truck starts after a few tries, and then runs erratically, revving up and down, chugging, and dying. sometimes it runs for ten seconds, and sometimes, ten minutes. So, in trying to get it to my house, it kept dying when i would hit the brake, and somehow my friend got it home without the brakes. The distributor, plugs, and wires are all good, and i can find no vacuum leaks anywhere. I have unplugged the MAF (assuming it is the big plug on the left of the intake manifold where the hoses go in) the IAC, and EGR, with no change in how it runs. This is my first throttle body injection vehicle, if it was modern, or even carbuerated, i could keep troubleshooting, but it is cold outside and i am out of ideas.
Thanks for the help ahead of time,
liam
Long story short, I am navy stationed in OK, and traded my d21 for this truck with a friend who was moving to California, as this beast wouldn't pass their emissions, so history on the truck is kind of spotty, here is what i know after a month of driving it:
At some point, it was a 5.8(?) when you run the vin, that is what the build was.
It has 206k miles, and overdrive trans.
In the cold it needs to be started a few times as it would cut off after a minute or so.
anything past half throttle, and the motor would cut out, and then back on at the original rpm (approx, i don't have a tach)
Sunday night, i filled up the rear tank, on my way home (in the rain), the O/D light began flashing, and the transmission started jumping gears, and the engine started jumping revs, before finally shutting off and not starting again. Monday, i started troubleshooting and had no fuel pressure on the rail. So, since i could hear both fuel pumps priming, i replaced the fuel filter, now i have plenty of pressure, but the truck starts after a few tries, and then runs erratically, revving up and down, chugging, and dying. sometimes it runs for ten seconds, and sometimes, ten minutes. So, in trying to get it to my house, it kept dying when i would hit the brake, and somehow my friend got it home without the brakes. The distributor, plugs, and wires are all good, and i can find no vacuum leaks anywhere. I have unplugged the MAF (assuming it is the big plug on the left of the intake manifold where the hoses go in) the IAC, and EGR, with no change in how it runs. This is my first throttle body injection vehicle, if it was modern, or even carbuerated, i could keep troubleshooting, but it is cold outside and i am out of ideas.
Thanks for the help ahead of time,
liam
01-23-2017, 01:37 PM
#2
Senior Member
It sounds like a MAF problem to me. Understand you've unplugged it and tested but if it's defective unplugging it wouldn't change the condition. Someone else on here might be able to tell you how to troubleshoot it but you should be able to grab one for cheap at a scrapyard and replace and see if the problems go away. Not sure what year your truck is - if it has OBD/OBD2 you may want to try seeing if there are any stored codes and clearing them after you've noted them.
01-23-2017, 02:21 PM
#3
The MAF wouldn't be on the motor, it would be on the airbox beside the washer bottle. If it's a 5.8 (what does it say on top of the upper intake ?) they mostly didn't come with MAF - maybe 96 did but I haven't seen one yet.
Just unplugging things isn't a very good test really. Get a multimeter ($16) and look up how to test things. easyautodiagnostics.com is a good site.
3 things come to mind when you describe your symptoms;
1- alternator. Is it charging ?
2- fuel pressure; you say you have lots but exactly how much ? you need a minimum of 30 psi to run the truck (barely), you want to see closer to 45 psi. Your own fuel pressure gauge ($45 ?) would be a good thing to own.
3- TPS could be acting up, it can be tested.
Those are what I would consider the most likely, but after that it gets a little trickier to narrow down.
Your truck does have a program in the computer to help you try to narrow things down - you should pull the codes.
When you post, it's a good idea to include info about the truck to make it easier for people to help you - they look very similar over the years, but a lot of things changed year to year.
Just unplugging things isn't a very good test really. Get a multimeter ($16) and look up how to test things. easyautodiagnostics.com is a good site.
3 things come to mind when you describe your symptoms;
1- alternator. Is it charging ?
2- fuel pressure; you say you have lots but exactly how much ? you need a minimum of 30 psi to run the truck (barely), you want to see closer to 45 psi. Your own fuel pressure gauge ($45 ?) would be a good thing to own.
3- TPS could be acting up, it can be tested.
Those are what I would consider the most likely, but after that it gets a little trickier to narrow down.
Your truck does have a program in the computer to help you try to narrow things down - you should pull the codes.
When you post, it's a good idea to include info about the truck to make it easier for people to help you - they look very similar over the years, but a lot of things changed year to year.