StevePew

I have a 1988 Nissan pickup that seems to "run out of gas". When the weather gets cold or damp it starts missing and cutting out. The first half of the throttle won't get the truck enough gas. I just goes lean and bucks or cuts out momentairly. The only way it will run is to get the truck moving, put it in one or two gears too high and keep the throttle to the floor.

The pickup has done this annually for years, fall and spring in Texas, but now that I've moved to the midwest where its really cold it does it all the time. It just won't run. Three Nissan dealerships in three states have unsuccessfully thrown parts at the problem. Here's a short list of what I've had done:

Replace fuel pump filters. Each diagnosis says the fuel pump is fine.
Replaced the distributor
Replaced the spark plugs and wiring
Checked out the computer
Check out and replace various vaccuum hoses
Replaced both coils
Replaced the intake manifold gasket
Replace the alternator?? (They said it was spiking 16 volts and shorting out the computer. Sounds like bunk to me but it still cost $500)
Cleaned out the tbi

I've asked about the fuel injectors/electronics in the tbi etc but I'm patted on the head and assured I don't know what I'm talking about. This sounds like a fuel problem to me. If this were a carbureted engine it would be an accelerator pump problem or a fuel pump problem. I don't know much about tbi's.

The curren Nissan shop now wants to replace the ERG valve, change out the exhaust manifold etc. Any advice on what the real problem might be would be greatly appreciated.

Steve

jadcock

I'm not intimately familiar with the TBI system either, but here are a few thoughts:

1) Did they also replace the ECM after replacing the alternator when they did that? I would assume yes, but you didn't mention it in the post. I wonder if it's possible that they were actually correct, but never replaced the ECM after they did the alternator?

2) The current shop wants to change out the EGR valve...I'd try this first before paying them to replace a part that may not be bad. Find the EGR valve and disconnect the vacuum line that feeds is. This will keep the valve closed at all times and should alleviate the problem, if it is indeed the EGR valve.

3) I'd also look at the Fuel Pressure Regulator (FPR). It almost sounds like the diaphram is bad, and it's letting lots of fuel into the manifold unchecked. Sometimes, they make an FPR rebuild kit (which consists of the diaphram and o-rings) or sometimes you have to buy the whole thing new. Check the vacuum line between the FPR and intake manifold and see if it's wet (shortly after you turn the truck off). It should NOT be wet; if it IS wet, that's likely your problem -- get an FPR rebuild kit or replace the FPR.

It sounds like the shops you've been to keep getting you to pay them to put new parts on, without any form of assurance if that actually fixes it. Whatever you do from here on out, I'd ask them how they got to that diagnosis and why they think that part is bad -- and if it doesn't work, what recourse do you have (if any).

Good luck,

__________________
Jason Adcock
Always Tread Lightly!
1995 4x4 XE King Cab - 189,000 miles
1997 Cadillac Seville - 141,000 miles

aaronford

My dad's 89 TBI did this twice. Once it was the filter screen around the injector and the second, it was a bad coil. Remeber, you have two coils. Cold weather almost makes me believe you might be getting some fuel in you water tank.

__________________
Aaron Ford
95 2WD Nissan PU E
2002 Oldsmobile Intrigue GX
"The hard part about playing chicken is knowing when to flinch" Scott Glenn in The Hunt for Red October

StevePew

Thanks for the hints. They all seem more plausable than replacing the exhaust manifold which is the current shop proposal.

When they replaced the alternator, they did not replace the ECM. They said they checked it and it was "OK".

Thanks again

Steve

StevePew

I've replaced both coils which didn't fix the problem. The bad filter screen is a good idea. I'll check it out.

Thanks

Steve