I am having a problem with my 91 F-150, I am pretty sure I have a leaking injector, when it sits overnight the fuel pressure in the line drops to almost 0 and creates a hard starting condition, If I cycle on and off the ignition 4-5 times to build the pressure back up before starting it there is not a problem. I have already replaced the rear pump and fuel pressure regulator, the front pump is currently dead.

What I want to know is can the injectors be replaced without removing the upper manifold? It looks like I may be able to do it but looks are often times decieving. I want to try to find the one or two that are leaking instead of replacing them all (unless someone knows where I can get a set for a lot less than $200), But if I guess wrong I would rather not have to take the manifold off 3 of 4 times. Any help would be appreciated.

 

It is normal for the fuel pressure to drop to zero overnight, it's when it drops to zero very quickly after shutdown that you have a problem. If the pressure had dropped after 10 minutes I would worry about a leaking injector. You didn't mention changing the fuel filter. If you haven't, I would do that first because it is probably your problem.

 

The chances are good that the check in the pump is bad. It could be an injector but it would start flooded.

 

I already replaced the fuel filter, when the midship tank did work it had the same problem, and the rear pump was just installed two weeks ago, it made no change in the fuel pressure issue, so I dobut its is the check valve.

The pressure drops about 10psi per hour. Does that sound about normal?

Maby I have a different gremlin causing the hard starts, wouldn't suprise me on this truck, I have only had it 3 months and have already replaced:
Transmission (A4OD, a buddy rebuilt it for me)
Thermostat
full tune up
distributor (pip sensor was bad)
ignition control module (replaced before distributor, probably not bad)
O2 sensor
EGR sensor
Cleaned the IAC
New battery (the one it came with was 400ca, looked like it came out of a lawn tractor, not bad but I didn't want to rely on it come winter)
New starter
Rear Fuel pump (and still needs the front pump)
regulator (probably wasn't needed)

I guess you get what you pay for, even with all this I still have less into it than its worth. So its not all bad.

How I drove this thing home I don't know, But I have managed to eliminate all the computer codes so I think I am nearing the light at the end of the tunnel. Funny thing is, aside from the fuel pump and starter issues, it has been drivable the whole time.