72 D-Jet trouble

[jtencer]

Ok...let me begin by stating that I read the D-jet article by Nelin. My '72 1.7 has good compression, good ignition, recent valve job, dwell and timing set. Checked all static values using an ohm meter of all sensors, including pressure sensor (held vacuum too). Engine runs extremely rich leading to fouled plugs and gas in the oil. Next in the process was the injector flow test where I'm sure I found the problem. Cranked the engine for 15 secs with the throttle open and received a whopping 40cc of gas per injector! I know this can't be right...Nelin's article stated around 7-8cc is the norm. My question is where should I go from here? Replace the pressure sensor? Maybe the next step should be renting the FI tester from those great guys at Pelican.

[This message has been edited by jtencer (edited 09-16-2000).]

[Jim Smolka]

We need some more information.

Are the injectors pulsing or are they running continuous???

Have you check your fuel pressure??? What about the fuel pressure regulator. Also, plug the fuel line to the cold start valve. It may be leaking...

As always... my $0.015 worth

------------------
Smoke Daddy

[jtencer]

Good input. Is there an easy way to check if the injectors are pulsing or running continuous? Do I need some fancy piece of equipment? Also, fuel pressure is holding steady at 28 PSI and the cold start valve is not leaking.

Originally posted by Jim Smolka:
We need some more information.

Are the injectors pulsing or are they running continuous???

Have you check your fuel pressure??? What about the fuel pressure regulator. Also, plug the fuel line to the cold start valve. It may be leaking...

As always... my $0.015 worth

[jmcleod]

i had a problem with my engine flooding when i tried to start it. i traced the problem to the head temperature sensor. somewhere on this site is the specs on hot and cold resistance values. try that in your course of troubleshooting.

[Dave at Pelican Parts]

To check if the injectors are continuously on or not, you need a jar and a friend. Stick an injector in a jar, unplug the coil and all of the other injectors. Have a friend crank the starter motor. Watch to see if you get individual spurts of fuel, or just a continuous spray.

--DD

[jtencer]

Ok...did the injector in the jar trick and the injector provided a continuous spray. Also, a friend provided an LED light to plug into the connectors. I had a constant light for all. Checked the wiring harness to the brain and everything ohms out correctly. I'm beginning to think I'm one of the few with a bad brain...any thoughts?

--John

Originally posted by Dave_Darling:
To check if the injectors are continuously on or not, you need a jar and a friend. Stick an injector in a jar, unplug the coil and all of the other injectors. Have a friend crank the starter motor. Watch to see if you get individual spurts of fuel, or just a continuous spray.

--DD

[John Rogers]

The injectors should most definately pulse when cranking. The brain could be bad and the easiest way to find a car with a known good one and do a swap to see if this cures the problem? This is what I had to do about a year ago. Good luck.

[Dave at Pelican Parts]

This seems to be one of the typical ECU failure modes. I think one of the output transistors fails or some such electronic badness. Jim T. or "Box-ter" Bill would have a better idea.

Anyway, I have heard of two cars that have had this failure so far. Both were traced to the ECU. I would say that the ECU is almost certainly the problem.

--DD

[jtencer]

Ok guys...thanks for all the help. Replaced the ECU and no more fuel dumping out of the injectors. Fuel injector flow and spray checked good. Changed the gas diluted oil and fired it up...no smoke! Runs steady with no idle hunting. The story doesn't quite end happy though. I fired it up and drove about a 1/4 mile to get gas. Started it up again and drove about another 1/4 mile to a friend. Five minutes later it wouldn't start right up. The engine acted like it was flooding, after lots of cranking it finally caught. Drove it around for another good ten minutes and then home. I couldn't get it to do the same thing in my driveway. Any ideas?