shinrai

I’m pretty sure that when they fail they usually fail open meaning too much P to the injectors so the injectors can’t open. Some would electrically disconnect 1 injector to test (driving more current to the other 3) and try starting it.

Replace your FPR.

jksymz75

Thanks for the info, shinrai, I pulled one the injectors and it did indeed start up. Ordering a new FPR now!

Jfrahm

They do not often fail such that the fuel pressure is stuck high but anything is possible. If it starts on 3/4 fuel, it's possible a bad temp sensor for the fuel injection is skewing the system pig rich.
FPRs common failure is to leak out the vacuum side which also causes plug fouling.

jksymz75

So it wasn’t the FPR. Replaced with brand new, same problem - will turn over but not fire.

Is the temp sensor a logical next step?

Plug condition below.

Jfrahm

http://www.clarks-garage.com/shop-ma...9.htm#dme-temp

oz968

My money was on the FPR ...I lost !!

jksymz75

So this is interesting...

I used a noid tester to make sure all the injectors were getting signal - they were.

I replaced the new FPR with the old one since it seemed that wasn't the issue.

I thought I'd do a fuel pressure test cranking the car to see if I'd get a reading. Nothing.

Then I realized I hadn't fully tightened down the fuel pressure tester to the rail and it was leaking. Tried it again...AND IT STARTED RIGHT UP. Like nothing had ever happened. I don't get it.

Over the past few weeks, I've routinely just tried to start the car and it hasn't started. It had (sort of) started with one injector unplugged and also with starting fluid in the intake.

So what could've possible changed to allow it start now? I have since started it about 10 times and even driven it around the block and it's starting as normal.

Was something blocking something and shook loose? Once I drain more gas from the tank, I'm thinking to pull the strainer and see what condition its in. While I'm down there I'm going to replace the fuel filter.

oz968

Possessed ???

jksymz75

quite possibly.

Jfrahm

I have not seen a mention of testing or replacing the temp sensor. When I had this problem (on a Mustang) the sensor would fail intermittently and skew the system so rich it would not run. Sometimes it was normal for days.

jksymz75

Thanks for mentioning this. After that glorious few hours where the car started, I went out of town and came back a couple of weeks later and it wouldn’t start again.

I was doing some research and came across this video which troubleshoots the reference sensor. Not sure if that’s the same as a temp sensor:


It is my next plan of attack.

Jfrahm

No the reference sensor senses TDC. The temp sensor senses temp. There is one for the gauge and one for the DME.

Yogii

I really like this guys videos!

-Yogii
AKA 968 Novice