turns over like a champ but slow to start

[Catterman]

My 1990 B2 2.9 auto 4x4 has a hard time fireing. It will always start, but takes a lot (5-8 seconds) of turning over before it will. New battery, and newer starter and both work great. I tried turning the key to on and waiting a while to build up fuel pressuer but still no joy. I have tried turning the key on/off 3 times before starting but still that didn't make a difference.

Any suggestions as to what I should check out next? Thanks!

 

[wildbill23c]

Your high pressure fuel pump could be failing, or not functioning, I'd check it out. Usually with a fuel injection system the fuel pump will pressurize the fuel system as soon as you turn the key and wait a second for it to shut off then starting the engine, in your case its not receiving fuel, it may be sucking in air instead. You may need to purge fuel out of the system, look for fuel leaks as well, you may have a fuel line that's lose or leaking that is sucking in air rather than fuel during starting.

 

[Catterman]

I did just buy a "fuel injections pressure tester" from Harbor Feight. Is this something I can hook up somewhere and check out? Do you know what the correct amount of pressure is supposed to be? I will also check the lines for leaks, never a drop on the ground though that I can see. And at one time the fuel pump was replaced, as there is a hole cut in the floor on the back to access it.

 

[RonD]

+1 ^^

Getting a pressure reading on the injector rail would tell you more, it's called a Schrader valve, similar to a bicycle tire valve.
30-40psi is normal

I would spray some starting fluid in the intake then try starting, if it fires up right away then yes fuel is the issue, if it still takes it's time then spark would be your problem.

 

[wildbill23c]

Thanks RonD. Was just trying to find the details on fuel rail pressure. Definitely a help having a fuel system pressure tester. Make sure you purge the system though, as it can give false readings if there's air in the system rather than fuel, the pressure tester doesn't care if its fuel or air, it will measure it and tell you there's pressure there when in fact it may just be air LOL.

 

[Catterman]

Great, i will take a reading and let you know what it is.

On the same note, how do I purge air from the fuel system?

 

[RonD]

Same as letting air out of a tire, but put a towel over the Schrader valve as fuel will spray quite a distance at 30psi, you can hear if there is air mixed in with the fuel.

 

[Catterman]

Okay, I changed the fuel filter this weekend and attempted to hook up the fuel pressure tester, but I can't find where it goes! Does anyone have a good picture or know where to hook it up to?

Also, does this truck have a fuel injection pressure regulator that could be going bad?

 

[RonD]

2.9l should have the schrader valve(pressure reading point) and fuel pressure regulator(FPR) at the front passenger side of the intake manifold.

FPR will have a vacuum line attached, remove this line and smell it for gas, if FPR's diaphragm is leaking you will smell gas, replace FPR if you do.
FPR can still be bad but pressure test would be needed first.