Won't stay running

Desperado2 · 07-11-2021, 11:08 AM

I have a 1976 914 with d-Jetronic fuel injection. Was having an issue before putting it away for the winter. When I got it out of storage it seemed to start and run fine. Now the issue has returned. Car will start and run fine for about 25 minutes than will almost sound like it is loading up quits. Won't fire and run. I suspected the fuel pump but it seems to be fine. After sitting for a couple of hours it will start up and run fine again for about 25 minutes and then quit. Will turn over fine, just not fire up. Looking for any suggestions on where to start troubleshooting
Thanks

tonythetarga · 07-12-2021, 06:47 AM

You need to diagnose the 'fuel-spark- air' formula for running. I'd pull the plugs first and see what they look like. rich or lean??) That should give you an idea what to do next. Then I'd look at coil points and condenser if you're still using original equipment. Check spark strength and gap. Fuel pressure is another thing to look at. You can put an in-line gauge in before the fuel rail to see if the pump is working well. Post pictures of the plugs.

Desperado2 · 07-12-2021, 07:59 AM

Thanks for the reply I will proceed with your suggestions.

dr914 · 07-12-2021, 08:55 AM

sounds like a failing head temp sensor

Gianni at Pelican Parts · 07-12-2021, 09:46 AM

Have you checked out our "How To" Tech Articles for the 914 chassis yet? Lots of helpful write ups there about common issues and fixes.

GregAmy · 07-13-2021, 11:07 AM

I will offer, from spending a lot ot ime trying to troubleshoot my D-Jet running problems, that the MPS diaphragm has a limited life and will eventually fail.

By now, if you've has not been replaced iwth new in the last decade-plus, it's probably failed.

Consider sending it to Tangerine Racing and ahvign Chris rebuild it. He has had the diaphragms reproduced from the correct Berillium-based material, and they should last you for a very very long time.

MPS Repair Kit

After pulling my hair out, I finally gave mine to Chris to rebuild (despite it actually holding a vacuum); they found the diaphragm cracked. The replacement transformed my experience with the car.

tx93086 · 07-18-2021, 08:28 AM

Two things might cause your issue and they are easy to check. It is not uncommon for a failed ignition coil to behave the way you describe (intermittent failure that is temperature sensitive). Check the spark when it won’t start. A failed (open) cylinder head temp sensor will make the car run extremely rich. When it exhibits that behavior, short the wire to the sensor to ground. That will lean it out, but it will still run if it is warmed up. I have also seen bad rotors in the distributor be intermittent, and a significantly too narrow point gap could behave that way. All are easy fixes.