Help: 86 930 starts but stalls after 10 seconds

[brasch]

I have verified all the relays, pumps and safety's are working, does the same thing no matter what I do. Starts right away and idles fine, then stalls in 6 seconds, fuel pumps still have power right after stall and then 1 second later are no power, which is how it should be I assume. If I give it gas it revs a bit but stumbles and dies too.

What do I test next?

Here is a video of the typical reaction, it will start right up every time after it stalls.

https://youtu.be/5EYQ7sp4iAo

[brasch]

With key on I get no power to the + side of coil when it runs its only 3-4volts? Is that right?

[brasch]

Looking at test procedures I guess I can't test the coil feed since it is suppose to be 460 volts.

Some more questions:
1. If the front pump is not pushing enough fuel would it start but then stall?
2. How much spark should the plug have on firing? I'll pull a plug and see how much spark I have, if the CDI is bad or. lol the spark would be low or none?
3. Would the WUR make the car behave like this? From what I'm reading it shouldn't make the car start easily and them stall in 5 seconds

[Jeff NJ]

Have you tested fuel pressure (system and control) with the car off, but the pumps on? This will tell you if the fuel pumps are working correctly.

[brasch]

I just ordered a CIS pressure test setup, that will be my first try I guess as it seems where everyone needs to start.. Make sure fuel is correct pressure for CIS

[RarlyL8]

Knowing nothing else but what I see from your video, I would say the ignition is being cut.
When you put the key in the run position the CDI will energize. When you turn the key off the CDI will remain energized for a few seconds then shut off. This is what it looks like is happening. If so the problem could be anywhere from the key switch to the delay relay.

[brasch]

I bypassed the delay relay so it could be the switch? How do I test that?

[jsveb]

Sure seems like ignition. However, how about removing the air filter and press very gently down on the metering plate. This should overcome a rising control pressure, somewhat ruling out fuel.

[brasch]

I tried that and it doesn't help at all, it still ends up stalling out

[RarlyL8]

Hot wire the ignition circuit (bypass the ignition switch).

[brasch]

From my reading it seems like a bad CDI would cause the car to not start at all, is that correct or if the voltage to the coil is too low would it start and then stall like mine does? Or is it typically that the car won't start at all?

[RarlyL8]

The "typical" failure mode of a bad CDI is that it begins to break down when it gets hot, then fails.
What you have is predictable failure, and the few seconds the engine runs is the clue. Once the engine dies you have to figure out what lost power while the key remains in the on position.

[flightlead404]

Others have mentioned the delay relay, I think its related.

Fuel pumps don't have power when it dies because airflow meter safety switch is cutting the ground when the plate is not deflected.

I wonder if there's a bad/intermittent connection on the ignition switch in "run" position, but the power is there in the "crank" position. That would allow the car to start, but as soon as you release the key it is relying on the delay relay.

Have you checked power at the pin on the CDI box?

[brasch]

Thanks I did jumper and bypass the delay relay and overboost sensor and it did the same thing. I got my CIS troubleshooting guide and found this section, sounds like my symptoms, so checking fuel pressure will be first once I get the test rig.

[T77911S]

if you bypassed the delay relay and it did the exact same thing then its not ign.
you sure you bypassed the delay relay? that sure looks like what is happening.

remove the connector on the top rear of the AFM. turn key on and verify pumps will run longer than 6 sec. if you can, monitor fuel pressures and verify they go up as the WUR is heated.

you could also check fuel flow to the WUR. I think its 220ml in a minute.
fuel flow out of the FD return to the tank could be checked too.
how is the fuel filter


will it restart after dying?

[brasch]

Yeah I jumped and bypassed the relays for all including the pumps to check if anything was the issue, same symptoms.

It will restart right away and do the same thing

[T77911S]

turn the key on and verify the FV is vibrating. make sure it keeps vibrating.

if both FP relays are jumpered that removes a LOT from the problem. (speed relay, yel rely, overboost sw, wiring).
actually I think it would eliminate fuel unless you are out of gas, (seen one do something similar with no gas but it would not run that long, about half that).

you sound like you know what you are doing and I hate to ask again but are you sure you jumpered the correct delay relay. it runs as long as the relay would be active on powering the car off.
the other thing is what ever the issue, it resets after its off. that would also lead to the delay relay as power would be reapplied to it when starting and that would start the process all over.

the only other thing I can think of is the screen in the fuel tank collapsing and stopping fuel, if that's possible.
you could try what I said above, fuel flow tests.
jumper the FP's and run them for a minute then start. if no start then you have a fuel flow problem.

[brasch]

Checked spark today, strong and white even after the car stalls, so based on some testing I think the rear pump is bad, at least it isn't the CDI

[T77911S]

remove connector on rear of AFM.
remove both FP relays
turn key on.
put one relay in and listen for pump,
remove relay
put other realy in.


problem with the spark test is the car restarts after it stalls. if it is the delay relay when you turn the key to start you are starting the whole sequence all over, like a reset.

try turning the key on and listen for the CD unit. if you can hear it, leave the key on and see if the CD stays on past 6 sec.

don't leave just one relay in for very long.

[brasch]

I got it back running tonight, replaced both fuel pumps, but it looks like a restriction in the front fuel feed hose from the tank may have been the culprit. When I removed the front pump fuel drippled out the hose, my son noticed that there was rubber blocking most of the inside. Looks like the pump sliced a piece of the rubber off as I installed the new hose and it all but plugged the line!

Took it off the lift tonight and ran it up and down my 400' driveway for 30 minutes! Yippee back to finishing things up to get it on the road!

Thanks for everyone's help, I guess the insight is that fuel starvation acts like other issues