bad fuel regulator

[captek]

I have a 1990 c2 with fuel pressure of 60lbs,I think Ive traced it to a bad fuel regulator.I know it should be 30lbs,the car runs poorly if it runs at all.Ive have never changed the pressure reg while it was in the car.Its real easy when the engine is out of the car.Whats the best way and fastest way to replace the regulator?Thanks for any help at all.Captek

[colo964]

Actually 60 psi is about right - the spec when shorting #30 and #87b on the DME relay is 3.8 +/- 0.2 bar putting right at 60 psi. It should drop to 3.3 bar when the motor is running.

Try popping your speedometer and see if therer is a socket for the CEL (my 90 has one though it isn't supposed to). If that is lighted - you can start to diagnose electrical parts.

An easy one is undo the O2 sensor wire - it'll run rich but will run compared to a bad signal from the sensor.


BTW, The fastest way is the only way with the engine in - about a 2-3 hour job. Take off one side of the air intakes (I like the side with the air box). You might need to take off the throttle body too. There it sits. See page 62 of the parts catalog.

[captek]

Hi,thanks for the help.I changed the reg,did it without taking aNYthing apart except for the afm.Was not that bad.The pump now holds press when you shut the car off.The problem I,was having is the car was running rich,fouled the plugs not oil but gas.Car was almost shutting off would not idle almost did not make home.Hard to start when hot.Changed the plugs,replaced the coils with two msd blasters changed the head temp sensor.Car also has a new o2 sensor when I redid the engine.Drove it and it was slighty missing,but ran up to 7,000 rpm under load quite a few times and it cleared up the miss and started to run well. The only thing is when the car is parked and you goose the throttle I still feel a hesitation in the throttle response,though not when I,am driving the car.I dont have access to a hammer,the dealers on long island are ripp offs.Car starts right away now.I know this car and its not 100% even though it runs good.ANYbody know of someone with a hammer on long island NY I could have it checked for codes?ANY suggestions appreciated.Captek

[colo964]

Poor hot start, erratic idle and runs-rich?

Start with this....

Check the temp sensor (the plug is behind the rear blower, or on pins 30 and 45 on the 55 pin plug). It should read 1500 to 3000 ohms at room temp. It will drop to 200 to 400 ohms at operating temp, but it should be a good/no-good reading at room temp so don't bother heating it up.

Check the injector voltage at each wire = 12-14V with the key switched on.

Check the injector resistance = 16 ohms at the injectors themselves.

If poor starting at any temp is your symptom, also check the idle switch. Cable should be slack enough to engage it and it should read <10 ohms at idle and open circuit when the pedal moves just slightly.

Let me know what you find.

[captek]

Hi thanks for the help.I changed the temp switch,car runs good but still has a slight hesitation when you goose the throttle when stationary ,but when driving there is no hesitation.i was wondering if there is a throttle switch on these cars?If I cannot locate the problem I have to get a hammer hooked up.Thanks Captek

[colo964]

There are 2 throttle switches, but hesitation is a symptom only for the WOT/high rev switch. There are 16 other items listed for "hesitation" on the check list, but only the WOT and knock sensors have it as main symptom.

I know of no good way to test the knock sensors.

Maybe recheck your plugs, if you were running rich, they are carbonized. Do an Italian tune up.

Also pull the AFM and shake it or crack open the black lid - could be a broken arm inside.

[captek]

Hi,I changed the air flow meter,I just happened to have a brand new one in the box I had from about six years ago from another car I had.No change at all I put the old one back on the car.I will have to get the durametric system or the find someone with the hammer.Thanks Captek