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914World.com _ 914World Garage _ Engine turns and fires, then revs then dies

Posted by: echocanyons Apr 17 2005, 04:54 PM

Sorted through the fuel pump issues that I was having with the boards help.

Went through the vacuum hoses for the FI system and it all appears to be correct.

car is a stock 72 1.7 D-jet
NOW:

The car turn over fires then revs high to 3000 for a couple of seconds then dies.

I remember this happening to my 74 right after it needed a top end rebuild for failure of which I cant recall

How should I go about checking to see if the engine has had a failure

Compression test? anthing else?

Other open ended possibilities that run through my mind are MPS problems, incorrect fuel pressure cuz I still havent been able to find a guage/tester that I can run with inline with this setup.

Posted by: bd1308 Apr 17 2005, 04:58 PM

how does it die....just cut out and die (liek turning the key to off) or does it stumble and sputter

Posted by: echocanyons Apr 17 2005, 05:05 PM

It seems to start then rev high then tapers off then cuts off. The throttle does seem to have any effect on what the engine does either.

Posted by: Headrage Apr 17 2005, 05:08 PM

Maybe your fuel pressure is too low. Does you pump run. Why not jut go get a cheap 0-50 lb gauge and tap into the feed side and see what pressure it's got?

Posted by: ! Apr 17 2005, 05:11 PM

Pressure or filter....

Posted by: vsg914 Apr 17 2005, 05:22 PM

does the fuel pump run when the starter is engaged? Sounds like you are getting enough fuel to start when the key is first turned on, and the pump first runs. Make sure it continues to run when the starter cranks.

Posted by: bd1308 Apr 17 2005, 06:27 PM

ayup. agreed

Posted by: echocanyons Apr 17 2005, 06:44 PM

So I tested the PSI at the D side of the fuel pump =52 PSI

The reference I have says it should be 28.5-30.8 but I think this is after the pressure regulator.

I am going to attempt to tap into the regulator and meaure that

Posted by: Headrage Apr 17 2005, 06:48 PM

Mine was really high because the pressure regulator was in backwards. I don't know if the 1.7 has a cold start valve but you might also want to check down into the plenumn and take a look for a lake of fuel. Mine was forcing fuel through the valve and just dumping it in. I'm glad it didn't fire.

Oh yeah, injectors don't like high pressure.

Posted by: echocanyons Apr 17 2005, 08:02 PM

Across the regulator I measured 30-51 PSI

52 while cranking and 30 at rest.

Should I adjust the regulator so the peak is 30?

How do I tell if it is on backwards?

Posted by: ! Apr 17 2005, 08:04 PM

That's NOT bad....have you pulled a plug to see if they are wet? Are you sure you are getting spark? The injectors are pulsing?

Posted by: echocanyons Apr 17 2005, 08:06 PM

I pulled one injector and the spray looked good.

I havent pulled a plug, I guess that is my next step

Posted by: Headrage Apr 17 2005, 08:07 PM

QUOTE (echocanyons @ Apr 17 2005, 07:02 PM)
How do I tell if it is on backwards?

Is is basically a one way flow valve. Pull the line on the side currently going to the return and see if anything comes out.

I don't think you want anymore than about 30 lbs. of pressure. See if you can reduce the cranking pressure down to that and see if it is stable.

Posted by: vsg914 Apr 17 2005, 09:59 PM

52 while cranking is too high. There is something wrong. Maybe a kinked return hose, or like Allan said, the regulator is in backwards. The adjustable side of the regulator is the "out"side.

Posted by: echocanyons Apr 18 2005, 08:02 AM

This was not testing inline but rather at the line so in essence the return line was kinked with the pressure guage.

I will have to rig the tested with a tee so I can test inline.