88 3vze won’t restart after new fuel pump

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Brownfaux

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I think I’ve exhausted my searches, so I need some help now. Here’s the lowdown.

88 3vze was running and starting over the last summer. It’s my project so it sits for a while. Wouldn’t start a few months ago so I put a new fuel pump in after some troubleshooting. Started right up and restarted for me when needed over several days. Did the EGR delete, still started and restarted for me.

Sat for a month, wouldn’t start. Did some troubleshooting, thought the fuel pump was bad. Exchanged it, started right up. Let it run for a bit and it died when I put it in drive. Won’t restart.

Now, when I put the new pump in I didn’t secure the sender unit with the screws. I just hooked it up and dropped it in. I have since secured it and it won’t start.

Jumped the connectors at the diagnostic port, still won’t start.

Pulled the hose off the FPR and a little fuel came out, but it’s not gushing when I try to start it.

I have fixed the cold start injector and the coolant temp sensor in the past, it was a wiring issue and I don’t think they are the culprit.

Could my truck be ruining fuel pumps? Right now I’m thinking of a new gas cap, and maybe a fuel filter? Any help would be appreciated.






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Brownfaux said:
I could not. I don’t know how loud it should be. I didn’t hear it run when I started it the first time either though.


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You should hear it with the terminals jumped and the key in the ON position. Pull up the seat just to make sure, but you can hear it well from the driver seat. If it doesn’t run, you likely have a wiring issue to the pump or a dead pump. I’m betting wiring since you’ve replaced the pump before.
 
So my last pump, I put 12v to it directly and it barely made a sound. I can hear the pump in my 04 and my wife’s Tiguan easily.

Maybe my first pump actually died and now I have a wiring issue? Is it safe to put 12v to the installed pump to see what it sounds like?


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Brownfaux said:
So my last pump, I put 12v to it directly and it barely made a sound. I can hear the pump in my 04 and my wife’s Tiguan easily.

Maybe my first pump actually died and now I have a wiring issue? Is it safe to put 12v to the installed pump to see what it sounds like?


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When you jump FP to B+, you’re putting 12v directly to the fuel pump, bypassing all the other circuits and checks. If you don’t hear it run like this with the key on, you have a continuity issue or a bad pump.
 
Last edited:
Thank you. It appears to be electrical. I traced all the wires and couldn’t find an obvious fault. Put 12v straight to the pump and it started right up. Now the only problem is finding the bad connection.

I may splice into the harness near the passenger seat to see if the problem is from there to the pump, or from there to the engine bay.


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I’m wondering, could my relay be bad and maybe I messed something up near the diagnostic port? Anyone had a similar issue? I’m sorting through some search results but I’m trying to find a shortcut because I can either fix it in the snow or get people to come help me push it in my garage to take my time.


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When I had this issue a couple of years ago after a rebuild, the truck would idle for about 2 minutes then sputter out and die. I cleaned all the grounds, in some cases I had to strip back to clean wiring and replace the crimp rings. The problem went away. Check your grounds, the ones by the fuse box behind the driver side kick panel is where the fuel pump ground lives if I remember correctly.

EDIT: You put 12v to the pump by jumping B+ to FP and it started up? That’s pointing to a different issue other than wiring to the pump.
 
Last edited:
No put 12v direct to the pump via battery. I wonder if I’m making contact with the jumpers sufficiently.... let me check.


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Just put 12v to the harness connection point by the pass seat so all is good from there back.


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Put a jumper wire at the diagnostic ports FP and B+. Turn the key to on/start position. Listen for the pump to run. Do you hear the pump? You have to do this to work your way down the diagnostic process. If it doesn’t run, you’ve isolated the problem to the pump or open circuit to the pump. If it does run, you need to look further into the COR and VAF air meter system.

If you don’t trust the jumper connection is working, probe the B+ port with your multimeter and ground. Turn key on and check for continuity.
 
Yeah I’ve had it jumped. I’ll check the ground next. I’m going to let it sit for the week. Too snowy now.


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Confirmed, no power at the B+ port on the diagnostic. Time to check grounds and what not.


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Brownfaux said:
Confirmed, no power at the B+ port on the diagnostic. Time to check grounds and what not.


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Did you get a voltage reading at B+ ? Should be something measurable ideally above 12v but doesn’t sound like you are getting that. Check the obvious things first
 
After I posted that I checked again and got 3v. I can’t see anything obvious at the moment.

Nothing is unplugged, all grounds are secured, it’s probably something stupid. I’m just going to get it moved into my garage and take my time cleaning up the wiring to the battery. Is this still a circuit opening really possibility?


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Brownfaux said:
After I posted that I checked again and got 3v. I can’t see anything obvious at the moment.

Nothing is unplugged, all grounds are secured, it’s probably something stupid. I’m just going to get it moved into my garage and take my time cleaning up the wiring to the battery. Is this still a circuit opening really possibility?


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Yeah, low voltage like that, you're probably looking at something in the EFI circuit. You can systematically test all of that too. Don't throw parts at it. Do you have a service manual?
 
Last edited:
Awesome thanks. I’ve had some trouble locating the COR, can’t seem to find any results when searching for a first gen with 3VZE. I get a lot of results for second gens. I took out the glove box and unbolted the ecu and can’t see anything near it. If anyone knows where it would be on an 88 3vze it would be awesome. I’ll run down the list in that first link though for sure.


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