Hit a large bump in the road, then car died

Pchip · 07-31-2019, 08:48 PM

1987 911 with electromotive and PMO’s. Seems that the power to the fuel pump died immediately after hitting the bump. All other power seems fine. When I turn the key to start there is no fuel pump kicking in.

Thoughts/suggestions?

dreichman · 07-31-2019, 09:26 PM

Maybe there is a fuel shutoff that was triggered from whatever you hit as if you were in an accident.

trond · trond's Garage

check if fuel pump relay came loose. Happened to me

proporsche · proporsche's Garage

there is not fuel pump relay in 1987..Check your fuse number 6 from windshield direction.Check in the engine compartment on left side these 3 plugs if one of them got disconnected...

Ivan

Pchip · 08-01-2019, 04:21 AM

Thanks for the replies guys.

Ivan, #6 fuse was fine. My motor has been rebuilt and modified (Clewitt ITB’s, PMO’s, ECU) and I don’t see the sensor you are referring to. But i did find a series of ground wires that are supposed to be attached to a bolt coming from the frame on the left hand side of the engine bay. This collection of grounds were just hanging loose. I don’t have a metric bolt to fit at home but did just slide the connector on to the bolt to see if that works. Still no fuel pump.

Do I need to have a solid connection here to have the fuel pump function or do I have a separate problem I have to find?

proporsche · proporsche's Garage

that would the trick has to be solid ground -check them all .Send a picture of the engine set up.There is a ground strap on cyl number one has to be tight too..
Ivan

cabmandone · cabmandone's Garage

That series of ground wires would typically go to the intake runner on a 3.2 I think. Not sure what it would do in a system with electromotive and carbs since the electromotive controls ignition timing. Your fuel pump would typically come on while cranking in 3.2 with motronic. Check the hot side of your fuel pump fuse to see if it's hot with the key on. If it's not, jumper from a constant 12 volt source to the fused side of the fuel pump wire and listen for the pump.

My BIL had a problem with his fuel pump not coming on in his 914. Ended up being a wire loose in one of the original harness connectors. I'd start with verifying power to the fuel pump fuse and if no power you'll have to track back the wiring to see what replaced the signal from the speed/reference sensors and DME relay.

tmadden2 · tmadden2's Garage

Busted DME relay? That drives the fuel pump and the bump could have been the nail in the coffin for a dodgy solder joint.

I hit a speed bump once and dislodged the negative cable from the battery terminal. The car drove until I parked it, but wouldn’t restart. That was an embarrassing discovery.

LUFTKUL · 08-01-2019, 05:37 AM

Double check the ground boss that's threaded on the driver side intake toward rear of car. I had a no start on my '84 because that ground wasn't tight enough.

Pchip · 08-01-2019, 05:38 AM

OK, here is the engine bay:

The ground wires now reattached. Still working to get fuel pump running.

cabmandone · cabmandone's Garage

Have you ran a jumper to the fuel pump yet?

BTW, your engine was installed upside down.. It'll never run that way!

Pchip · 08-01-2019, 05:55 AM

Did not have a chance to jump the fuel relay. Car is on a flatbed heading to my mechanic so we can get it on a lift. Stay tuned...

DME relay sounds like a possibility as well.

cabmandone · cabmandone's Garage

Wouldn't the DME relay just be the fuel pump relay since there is no DME anymore with carbs and electromotive? I'm trying to find a thread on how the fuel pump is energized when the motronic system is removed.

Paulporsche · 08-01-2019, 07:14 AM

Are there round black connector plugs under the dashboard on the front "firewall" as there are on my 77? If so, make sure they are fully seated.

Jgordon · 08-01-2019, 08:12 AM

When you turn your key to the on position (before you turn the engine over) can you hear a whine from your trunk? If not, the fuel pump itself is dead.

Exact same thing happened to me. Big bump in road, car died, coasted to the side. Fuel pump had given up after 25? years.

Pchip · 08-02-2019, 05:03 PM

shop did a number of tests and the culprit appears to be the fuel pump. Won't know for sure till we drop in the new pump next week.
Seems flaky that a 3 year old fuel pump would fail with less than 500 miles on it. WTF?

Any thoughts?

cabmandone · cabmandone's Garage

Seems flaky but being an electrical/mechanical part, anything is possible. I'm assuming they put power to the pump as one of the tests. If the pump doesn't engage, bad pump.

RWebb · RWebb's Garage

Quote:

Originally Posted by Paulporsche

Are there round black connector plugs under the dashboard on the front "firewall" as there are on my 77? If so, make sure they are fully seated.

actually, just pull each one, spread the pin halves/ or quarters slightly, clean spray with a contact enhancement liquid and reinstall

that connector in the photo should be shiny and have dielectric grease on it then tighten down

RWebb · RWebb's Garage

Quote:

Originally Posted by Pchip

shop did a number of tests and the culprit appears to be the fuel pump. Won't know for sure till we drop in the new pump next week.
Seems flaky that a 3 year old fuel pump would fail with less than 500 miles on it. WTF?

Any thoughts?

not What TF but Where TF - i.e. is likely manf'd in a suspect country...

and no you cannot trust Bosch any longer

Pchip · 08-04-2019, 06:48 AM

Quote:

Originally Posted by cabmando

Seems flaky but being an electrical/mechanical part, anything is possible. I'm assuming they put power to the pump as one of the tests. If the pump doesn't engage, bad pump.

They did in fact put power to the pump and nothing, so a new pump will be installed tomorrow.

I have an itch to contact Bosch for a refund but suspect I will get nowhere.