awilli6

Hey gang,

I just replaced the coils, wires, plugs & caps on my 87 w/ 121K on the clock. It was getting more & more difficult to turn over & eventually started running on 4 cylinders. The issue was a corroded coil.

After changing all of the above items, it still doesn't turn over (vroom) like it did when I First got it. I have to give it gas to get it to catch. I've also changed the relays for FP, ignition & EZK.

What should I look for next.

James Bailey

Possibly the check valve at the fuel pump...or possibly the fuel damper or pressure regs are leaking fuel into the intake...

Turnover really means the motor turns / cranks on the starter motor......at first I was worried about thrust bearing failure !! When the engine goes vroom vroom it has stopped cranking and it is RUNNING !!

awilli6

Car idles a little rough when 1st cranked, but runs perfectly when warm. I have a clamp to prevent TBF. I don't smell fuel. Thanks for the guidance.

James Bailey

The rough idle is not normal...when the pres regs leak it goes into the intake via the vacuum lines and floods the engine. Holding down the gas pedal adds more air so it can start. All that holding down the gas pedal does is let in more air so if that seems to help perhaps there is too much fuel ....

Cranking is whaa, whaa, whaa which is also turning over......starting running is vroom, vroom .

It would be good information to see what a spark plug looks like after you crank it a bit and it does NOT start....

awilli6

It always starts, just longer cranking. Always starts during first crank attempt. Just not ant immediate start.

awilli6

Ok guy. I'm asking again on the same difficult start topic. When I park the car with engine downhill, it fires right up. When it's even, it takes several cranks before vroom. I changed everything listed above & the three important relays. Could this be early fuel pump failure? Or is it possibly crank position sensor? Any other thoughts? It runs perfect once started.:

James Bailey

You might want to install a fuel pressure gauge on the fuel rail to test how long it is holding pressure and how long it takes to make pressure when you start to crank it on the starter motor....
You could install a temp jumper switch so you could energize the fuel pump before you actually start cranking to see if that gets it to start quickly. Just do not run the pump very long with the engine not running.

awilli6

Thanks for the info James. Is there a write-up on how to do what you suggest? I have to say, I've accomplished great deal with this car mechanically, but it's been accomplished using all of the info the actual mechanics on here provide.

I follow directions very well. If you point me in the direction, I'll proceed as ordered.

awilli6

Oh, just so you all are aware, I take credit for the knowledge I acquire from you all when I'm explaining to others what I've done

dr bob

Do you have a hand vacuum pump tester gizmo like a Miti-Vac? It's virtually a requirement in the 928 DIYer's tool collection. If you have a Harbor Freight nearby, I think I saw a kit with the pump, hoses and adapters, and a brake bleeding cup for low $20's range.

Anyway, verify that the fuel pressure regulator and dampers hold vacuum. Good idea at the same time to test from the end of the hose to throttle body. Dribbling fuel or an air leak might cause some of your symptom. After those, temp-II and the MAF would be high on my list to look at. The thing that thows me is that you say it starts fine from nose-down position. [scratches head] Just not dialed into what might make a difference enough to cause that.

awilli6

Dr Bob, yes I have a mighty vac. I'll check those items this weekend. Yes, when I back up the hill & leave it like that on the incline, there is about 1/2 revolution of cranking before vroom.

danglerb

Is this still an issue, rough running when first started cold?

If so maybe IAC or temp II.

Down hill, maybe parked even fuel is draining back to tank?

awilli6

It really doesn't run rough, but because it struggled to start (run), it's not as smooth as it is after 10 seconds or after I press the gas pedal a little to help it after is running. It tends to smooth out pretty quickly.

terry gt

Could be a voltage drop when cranking , have you cleaned you grounds ?