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Hi, I am having a problem with an 89 gtu 2.8. I had an injector failing after the engine warmed up. Changed it and checked the others while I had it apart. Put it back together, and ran fine. Then it started a running like its not getting enough gas. Only when I first start it and try to accelerate. It only does it when the outside temperature is warm or when the engine is warm. It also goes away after driving for 5 min. It runs completely fine. I cleaned the throttle body, changed the tps, map sensor, and the temperature sensor for the computer. Still does it. I purchased a new o2 sensor. Just didnt get it in yet. The egr valve seems to be working properly also. Maybe o2? Maybe pcv valve? Thanks in advance!

Dirty MAF?

Check your FPR.

My mistake. FPR is Fuel Pressure Regulator. But you could have an issue with the fuel pump itself too. Make sure you check the fuel pressure at the rail.

Changed the o2 sensor. Still does it. Fuel pressure checks out fine. This is driving me crazy!

The engine is doing it almost everytime i start it now regardless of outside temperature. It still smoothes out after just a few minutes or driving. Im going to mess with the egr this week.

Have you checked/cleaned the maf sensor yet?

I know older years had them like the new 96's unless someone "upgraded" it to speed density and removed it.

89's do not have the MAF.

X3 on the FPR.

ronaconda wrote:89's do not have the MAF.

X3 on the FPR.

90 Indy wrote:Changed the o2 sensor. Still does it. Fuel pressure checks out fine. This is driving me crazy!

I usually get ragged for suggesting something thats already been tested...

3X00-Modified wrote:

ronaconda wrote:89's do not have the MAF.

X3 on the FPR.

90 Indy wrote:Changed the o2 sensor. Still does it. Fuel pressure checks out fine. This is driving me crazy!

I usually get ragged for suggesting something thats already been tested...

Touche'

Seriously though, fuel pressure may check out fine but did he put a vacuum pump on it to see if it held vacuum??? That's the true test of an FPR.

I didn't tell him to check the fuel pressure. I told him to check the FUEL PRESSURE REGULATOR. Big difference. FP can be fine all day and the FPR can still be bad. Still waiting to hear how IT'S doing.......

A little defensive just like always... My comment wasn't even directed at you. But I would like to know how you could have perfectly fine fuel pressure but have a failing fuel pressure regulator thats causing a lean condition. I can't put two and two together. In my mind and world... when a Fuel Pressure regulator fails then its failing at regulating pressure... The only other way it could fail is to pull fuel through the diaphram which will also reduce the overall pressure and actually make a rich condition since you would be pulling fuel directly through the vac line into the intake.

A regulator is quite simple in operation when it comes down to it, there isn't much that can fail.

are you using the new style upper intake manifold gaskets? those old ones were the problem child of vacuum leaks. the new ones are like rubber/metal. the old kind are like a paper gasket.

Fuel pressure regulator checks out fine. There are new rubbery gaskets on the intake.

Gtu still does it. Going to change egr valve to see if it changes.