Starting Problems - Revisited

[Tx951Dude]

Okay, I'm replacing yet ANOTHER engine component this week in hopes of fixing my hot start issue. This week it'll be a new coil, next week maybe a battery then a week later maybe a new starter?

Here's the problem, my car starts without fail when cold or after having been driven for short distances. Even after long distances it will start provided that it is given sufficient time to cool down. It will not start after it has been driven for times over 15 minutes and the cool down time is less than about an hour or more. It's weird because it is not consistent other than what I've described.

Here's what I've done/replaced:

New fuel pressure regulator
New fuel damper
Rebuilt injectors (I did these myself)
New plug wires
New DME relay

In the plans for replacement:

New coil on order
New battery
New starter
New dist. cap and rotor

The problem does not seem to be electrical however but I suppose it could be. The starter turns just fine but the engine will not start. Any ideas?

[x15jq]

Maybe you should check your fuel pump check valve. I had this problem and I replaced the pump and valve and it went away. I would eventually get it to start, but I would have to crank it for like 10 seconds 3 or 4 times.

[DannoXYZ]

Hook up a scope and compare the speed/ref. sensor signals between a cold engine where it starts easily versus a hot engine when it doesn't start. The differnces in the signals will tell you right away what the problem is. This is the very first step in the DME/KLR test-manual. Saves you a tonne of time and money chasing your tail swapping new parts in unnecessarily.

[Tx951Dude]

Okay, the problem occured again last night. It's very frustrating!

I ordered a new fuel pump and check valve today so we'll see if that resolves it.

An update will follow.

[944 Ecology]

It sounds like you are leaking down the residual pressure in the fuel rail needed to keep the fuel from boiling and causing vapor lock.

Get yourself a fuel pressure gauge and see what happens to the fuel pressure when you turn off the car. If it drops below about 20 psi, you won't be able to get the car started when it is hot.

gb

[Tx951Dude]

So, if I'm loosing pressure once the engine gets hot would a new fuel pump and check valve resolve the problem?

[944 Ecology]

Possibly, but it could also be a bad injector or two, or it could be a bad fuel pressure regulator...

gb

[Tx951Dude]

Okay, I've already rebuilt my injectors and replaced my FPR along with the damper. Guess I may have to fork over the $400+ for NEW injectors if the pump doesn't fix it, lol.

[ae1969]

Spend 30 bucks on the guage first.

[Tx951Dude]

Fuel pump and check valve replaced. Fuel supply and return lines replaced as well, thanks to Bob and the crew at RUF auto!

We'll see how it goes. It's started every time since yesterday afternoon so maybe it's fixed!

[Tx951Dude]

Drove the car yesterday and it started every time without problem until I tried to start it about four hours past turning off the engine when I got home. I cranked and cranked and cranked it but the engine just would not start. At this point I suppose that I will try replacing one or both of the sensors at the back of the engine.