FI system wont stay running

[BuBBaStuBs]

I got the fuel injection system running on my 71 squareback last night but it only fired up and ran once for about 20 seconds I went to give it gas from the throttle in the engine bay and it died... Now the car will keep trying to fire but won't start up anymore. We had replaced the stock fuel pump with a vanagon fuel pump if that makes a difference as my dad was thinking one of the possibilities could be we are flooding it with a higher fuel pressure from the vanagon pump could this be correct?

[aircooledtechguy]

Obviously check for hoses that may have come off on the manifold. Since you have D-jet, Here's a couple things I would check:

1. Be sure you connected your pump pressure outlet to the correct hose. The LAST thing the fuel goes through is the pressure regulator before being returned back to the tank. If you have the fuel routed backwards, the regulator acts as a one-way check-valve and no fuel will get to the injectors and the motor will die after about 5-8 seconds and likely not re-start.

2. Disconnect the manifold pressure sensor (MPS). This is connected to intake plenum by a small hose and is really the heart of the D-jet system. Be sure that it will hold a vacuum. You can either put a vacuum pump on the hose or give it a suck with your mouth and see if the vacuum holds. If it doesn't, there is likely the problem or at least a big part of it.

3. With the engine cold (around 70F) check the oHms on the cylinder head temp sensor (CHT) that screws into the head near the manifold on the drivers side fwd. It has only one black wire coming out. You should measure about 2500 oHms of resistance (+/- 300 or so) when cold. Colder = more oHms; hotter = less oHms. This will leave you stranded when it goes bad.


My vote is for #1.

[BuBBaStuBs]

Thanks I'm going to pull the plugs and check them and the points to make sure they are good then will look into what you have suggested. Will post what happens.