The Example

'87 L98 A4 with 40,000 miles. I cranked it up for the first time this spring, took it 100 miles with no problems. Today, I cranked it up and pulled into the driveway. Forgot my sunglasses, turned the car off.

When I came back out, the car would not start. Starter cranks and cranks but it just wont turn over. Battery has a good charge. I tried both sets of keys to check if a VATS pellet is the issue - it's not.

I want to check for spark and fuel - what are the simplest/cheapest ways to do this?

Suggestions?

Thanks

~TE

vader86

Hook up a fuel pressure gauge to the rail, start it, note where the pressure steadies, then shut it off.

It should hold there for a while, if it drops then the injectors are bad and require replacing. That'll cause a hot start problem every time.

qws

When you turn the key on, do you hear the fuel pump turn on?

RRT vette

Both good points. You should hear the pump prime when the key is in the on position for 2 sec. If not, and the car has had no problems til now, the pump is froze up or the relay went bad. The oil pressure switch is a back up for the relay and when oil pressure reaches 4 psi it should run the pump, but could cause you to crank longer. There also might be a spark issue. I would first listen for the pump, then if you don't own a fuel pressure guage (pressure should be 36-42 psi) you can press the valve on the schrader valve on the right side fuel rail. It should release raw gas. If everything checks out o.k. then use a good spark plug and go to each wire plugging it in, and hold them up to the exhaust manifold (about 1/2" away) while someone cranks and check for spark (after you take the 2 injector fuses out). More to come with new info.

rick lambert

All good information...but you do need a fuel pressure guage...this is what I do, connect the guage to the schrader valve on the rail(passenger side, looks like a tire valve) don't forget to wipe off any fuel leakage, turn the key to the ON position..don't start! watch what the guage reads...if nothing happens, check the fuses, then if need be, run a jumper wire from the battery to terminal G of the ALDL, this energizes the fuel pump,..watch what happens with the fuel guage..if the pressure goes up..turn the key off, see how far and how long it takes to bleed down..if it does!

Fuel pressure guage around 35 bucks!

RRT vette

Yes, this is the way to check the circuitry to the fuel pump. You can also check the relay... use a light tester at the fuel pump fuse and turn the ignition on. If the relay is good it should light up for 2 sec. With help of these guys this is a easy fix. The fuel pressure guage is a must along with the FSM for any thing like this. Let us know.