Starts only when I give it throttle and cuts out immediately when I release.

[BMdoubleYou]

Dear all,

I was tinkering with the electrics under the dash, under the gear stick and around rear light clusters of my ‘87 coupe when trying to fix a no brake light issue (resolved) and no reverse light issue (not yet resolved). Anyhow upon turning the ignition when testing the said lights I noticed that I didn’t hear the usual “relatively” audible buzz for a couple of seconds that I normally hear (anyone know what that buzz is?) but I paid no mind to it. Later on the day as I fixed the brake light issue to fire her up, the car cranks but doesn’t turn over. The only way to get her started is to give it some gas and holds as long as I keep the throttle open but as soon as I release from the pedal the engine cuts out.

I can hear the dme clicking on when the ignition is on and have checked voltage on the dme which is fine. I have bridged the fuel relay and can hear a small hiss as well as feeling the fuel passing through the fuel hose going into the pressure regulator.

Does anyone know what this could be? I am stumped. Car was driving beautifully before I fiddled under the dash..

Any help will be much appreciated. As I’m tearing the few hairs on my head out…

[82eye]

can't see it being related to what you were doing under the shift boot. buzz may have been the fuel pump priming.

probably time to start delving into the diagnostics. there's a number of things that can create the symptoms you have.
start here : https://www.r3vlimited.com/board/for...12#post6384179

[BMdoubleYou]

Thank you for the reply! I have looked into at that post, I will go ahead and start a vacuum leak test as it’s good practice anyway.

I do also think that buzz was the fuel pump priming although I’ve been reading conflicting posts about the fuel pump does turn on until crank etc.

I’ve certainly been trying to track down whether I have an electrical issue to the fuel system, simply because I am not hearing the buzz I used to hear. I’ve removed the ICV and given it a clean, it wasn’t dirty much but even after cleaning it’s still a bit sticky. I change a small issue generally when taking my foot off the gas and the rpms drop below 8500 to around 7000 before picking back up. I’ve resistance checked it with my trusty multimeter and all seems to be within range. I’ll see how it behaves. I could be wrong but I’m concluding that it isn’t the ICV as that should only be giving me idling issues given the condition of it.

I replaced the external high pressure fuel pump a couple of months ago from Bosch, and it is working as is when I pump throttle. I’m struggling to find out why it’s not priming…

[82eye]

I replaced the external high pressure fuel pump a couple of months ago from Bosch, and it is working as is when I pump throttle. I’m struggling to find out why it’s not priming…

possible the intank lift pump is tired or gone out as well. the external pump might be trying to pull the fuel on it's own. it would be good to tee a gauge on the fuel rail and check pressure as well. it could be a regulator problem. many times its a few little things adding up to one issue.

[It's Soda Not Pop]

Unless you're on a standalone the fuel pump only primes when you are actually cranking the engine over. At least on M20's.
Are you getting any codes when you do the stomp test?

[82eye]

Unless you're on a standalone the fuel pump only primes when you are actually cranking the engine over. At least on M20's.
Are you getting any codes when you do the stomp test?

on both dual and single pump cars? i thought dual pump cars primed. note taken.

[It's Soda Not Pop]

on both dual and single pump cars? i thought dual pump cars primed. note taken.

Dual pumps may differ. But I don't believe so. My car primes as soon as I turn the key over in the first position, but I have Jake's PNP.

[It's Soda Not Pop]

This is jakeb Channel on YouTube. This might help

https://youtu.be/mXnZQNzHgxY?si=eZt8D5ZbaOTi-e8C

[82eye]

This is jakeb Channel on YouTube. This might help

https://youtu.be/mXnZQNzHgxY?si=eZt8D5ZbaOTi-e8C

thanks for the link.

[It's Soda Not Pop]

thanks for the link.

No worries you're welcome