Turbodan

guys my 90 951 has a no start issue.
I was at Mosport on Friday and Saturday and it ran great but did have trouble starting a few times where had to turn over a few times before firing.
Sunday morning it would not start. the tach is staying very low and moving tiny amounts not close to 1000. It appears the fuel pump is not making any noise. I did try the jumper wires in the dme relay spot and no pump. I did test that the relay is getting power. would that mean the fuel pump itself?
the car has the ftech 9 diagnostic dme and I hooked up but can't figure out how to datalog. I am waiting for response from Joe. any ideas what is going on?
most of the wiring was replaced by previous owner Jerome and looks good. oh and there is a meter on the fuel rail and it shows 40 psi fuel on the gage on the dash (aem).

Turbodan

link to video of start trying:

https://photos.app.goo.gl/Tj2cgmgs3Fx787UbA

Turbodan

previous owner said he had a short at the fuel pump so going to check that out next.
any ideas/help is greatly apreciated.

Turbodan

I am confused because I am thinking if the fuel pump is not running, the tach should still bounce which it is not.
any thoughts? please help.

JustinL

That looks like a fuel issue as when it does catch, the tach comes up. Do that test again and pull a spark plug to see if it's wet with fuel. We had a similar issue with our enduro car after sitting for a year: the fuel injectors were clogged up and after cleaning them out, the car fired right up like normal. If your fuel pressure is good, then the pump is running... again making me think injectors.

Turbodan

will do shortly and will also try to datalog.
shouldn't the tach bounce higher when trying to start?or if no fuel that is normal?
thanks btw

931guru

squirt some starting fluid into the J boot then try to start it. If the symptom changes, focus on fuel.

Turbodan

well there was a short in the fuel injector wire to the cylinder closest to the firewall. I have swapped out two of the injectors as well as plugs and still same cylinder not firing. I have tested the injector wires using led test light and they are getting same signal. tested for spark using screwdriver and end of wire going to that plug and have spark (in case bad wire).
not sure what else except compression test. any ideas???

931guru

Time for a fuel injector test. Remove fuel rail with injectors attached, insert each injector into a coke bottle or such, jumper the dme relay so fuel pressure is built, then pulse each injector (for, say, 5 seconds... use a stopwatch) and see what comes out. The one that is not the same is your problem.

Turbodan

I did swap out the injectors already and the same cylinder is not firing.
I did tests with the led test light and found all the injector wires are showing the same reading.
I got a compression test kit and found cylinder holds 0 pounds of pressure, so it is internal. I also tested one other cylinder and got 60 psi.
I ordered a boroscope endocamera which will be here tomorrow
looks like the engine is gonna come out. I may have a low miles engine to put in.

931guru

If it is just a burned valve, no need to pull the engine, unless you like spending a lot of time working on your car.

If it is a scored cylinder or piston damage, then that's another story.

(Sorry, I never watched the video of your attempted start... classic sound of a dead cylinder... )

Turbodan

yes, hoping it is just the valve.