240 pre-pump advice

On my 90 240 2.4 M-47 trans. car, I'm having a problem with starting the car after letting it sit in hot/ humid weather. The first crank, I feel like it's starting, but doesn't. The second crank, it starts, but it's rough.



My voltage at the pre-pump (with engine running) is 10.67. At the fuse, the voltage measures 12.43. The visible wiring appears to look fine with no obvious breaks.



My battery is 13.6 V, and the main fuse under the hood connected to the battery is 13.5 coming from the system. The battery to right off the fuse blade is 13.4 V. These were also performed with the engine running.



I wanted to ask the experts before I went out and bought a new pre-pump in the event that I might have overlooked something more obvious



Thank you all for your help and suggestions in advance!

Ok, you got voltage to the pump, or at least a foot or so from it.

Can you hear/feel it run?

Disconnect the hose from the back of the pressure pump and see if you get any fuel out of it. It should only be about 7psi but be careful. Fuel everywhere is very dangerous.

Pre pump may be ok but the small hose attached to it may have a hole in it.

You may have a bad main pump check valve. You need to run a fuel pressure test along with a rest pressure test. If the pressure doesn’t hold for several minutes after the pumps run, that is probably your starting issue.

TestPoint said:

Ok, you got voltage to the pump, or at least a foot or so from it.

Can you hear/feel it run?

Disconnect the hose from the back of the pressure pump and see if you get any fuel out of it. It should only be about 7psi but be careful. Fuel everywhere is very dangerous.

Click to expand...

Thank you, TestPoint for the helpful advice,I removed the carpet and the plate to access the tank. With a tire iron pressed to my ear, I can hear it run. It doesn't sound erratic or anything like that at idle. I haven't yet unhooked the line to see if fuel is spurting out.

2manyturbos said:

You may have a bad main pump check valve. You need to run a fuel pressure test along with a rest pressure test. If the pressure doesn?t hold for several minutes after the pumps run, that is probably your starting issue.

Click to expand...

Thank you, 2manyturbos, I recall that the guy who owned the car before me mentioned that he replaced the check valve, but that was 5 years ago.

How long should the check valves last?

And,

Is there a fuel pressure test kit that you recommend for a non-schraeder valve setup? I've been meaning to get a pressure tester for a while now.

nel621 said:

Pre pump may be ok but the small hose attached to it may have a hole in it.

Click to expand...

Thanks,nel621;6103820 for the excellent suggestion. I'll have to check that on my next day off!

Just to provide an update. I looked under the car where the main fuel pump is, and I could see that the nylon tubing which goes to the pump from the fuel filter was slightly kinked. I'll be ordering one of those before it starts leaking!