96 5.0 XLT starts but will not stay running

[tjmaxx]

I got my Ex in march and it ran ok. I changed plugs and wires, oil and shocks, after that it ran great.I started driving back and forth to work about 20 miles each way and never had any trouble while driving. Then about a week ago I went to start it and it would fire up, chug a little then die. The fuel filter is also new. Is it the fuel pump or is there something else it could be?

 

[tjmaxx]

Bumping this up. I also pushed the fuel pressure relief on the fuel rail with the key on and gas came out it didnt shoot out.

 

[tjmaxx]

Help.

 

[gruss01]

Maybe the MAF? will it start and idle but as soon as you give it some gas it dies? Try cleaning that mass air flow sensor and see if it helps, can of contact cleaner could = cheap fix?

 

[Tom G]

Will it stay running if you keep your foot on the gas?

If so, it's prolly the IAC valve

 

[tjmaxx]

I can keep it running for about 10 seconds but continuosly.

 

[tjmaxx]

Sorry, I meant not continuosly.

 

[jimirig]

I am having the same problem with my 98 Exp 4.0. I starts fine but I need to keep giving it a little gas until a hear a pop noise that makes me think the IAC is not opening up right away. I'm am going to clean the IAC tonight and see if that make a difference. If not, then I will probably have to replace the IAC. I will let you know if I am successful or not.

 

[tjmaxx]

I cleaned the IAC and MAF and it still will not stay running. What should be my next step? Can the fuel pump be weak or do they go all the way out?

 

[tjmaxx]

bump.

 

[Turdle]

You could get a fuel pressure gauge and attach it to the valve you mentioned earlier.
this would tell you if you have a fuel pressure issue.

 

[tjmaxx]

Ill get one on monday. Can you tell me where the pressure should read at?

 

[Turdle]

should be around 35-45 psi

 

[tjmaxx]

thanks. I will update as soon as I can.

 

[David in NC]

You might also look for a vacuum leak.

My son's '97 ohv 4.0 died on him the other day. It would start easily and run a few seconds, then die. I could start it and rev it hard and it would run longer, then die. I looked around and found that the air box had slid off the throttle body. I slipped back on and tightened the clamp and he was good to go. He thinks I' a genius! I hope your fix is that easy.

 

[tjmaxx]

I checked the fuel pressure at the schrader valve and got nothing with the key on or while cranking. I checked the fuel pump relay and it is fine. Is there anything else to check before replacing the fuel pump?

 

[dkalleck]

I checked the fuel pressure at the schrader valve and got nothing with the key on or while cranking. I checked the fuel pump relay and it is fine. Is there anything else to check before replacing the fuel pump?

Check for vacuum leaks.
IAC valve is something cheap, replace it rather than cleaning it. If it ends up not being the issue, you aren't out much money.

Also, the fuel filter might still be an issue even if it's new. Double check it for good flow.

 

[james t]

Bumping this up. I also pushed the fuel pressure relief on the fuel rail with the key on and gas came out it didnt shoot out.

Its more than likely going to be the pump, going on this and your other posts. If you press the valve in with something fuel should shoot out.