1998 Ford F-150 Engine has intermittent rough idle and stall

CRW4719

MEMBER
1998 FORD F-150
6 CYL
2WD
AUTOMATIC
113,000 MILES

A couple of weeks ago my 1998 F150 w/5.4L started running and idling rough and has stalled a couple of times. No "check engine" light. I changed the fuel filter and cleaned the throttle body and mass air flow sensor. Though it ran better for a couple of days, the problems have returned but not as severe. In addition, I now have occasional problems starting the engine. It cranks fine and finally starts after 3 or 4 tries like it is starved for fuel.

Also, during this time my fuel gauge stopped working. At first it would drop to empty but in the morning it would be functioning again. It would work for a couple of days but then malfunction. The last 2 days the gauge shows empty when I have at least half a tank.

I'm not sure the two are related.

Thanks in advance.

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,779 POSTS

The two could be related because the fuel pump and float are one unit. I need you to check fuel pump pressure. Here is a how to for checking it:

https://www.2carpros.com/how_to/how_to_check_fuel_pressure.htm
Most parts stores will lend or rent the gauge needed. When you check it, pay attention to fuel pressure drop off. THat is when you shut the key and the pump stops. It should hold pressure or slightly drop. If it drops fast, that is why you are having a harder time starting it.

Let me know what you find.

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Wednesday, September 9th, 2009 AT 10:47 PM

CRW4719

MEMBER
10 POSTS

Tried several times to access Schrader valve to check fuel pressure but bi-fuel/propane hardware blocks access on passenger side near firewall.

The propane equipment was disconnected when I bought the truck 3 years ago. I find it really hampers my access to spark plugs, etc. Is it difficult/unsafe to remove? Can I just turn off the tanks in the bed and start disconnecting?

Since your response I replaced the air filter and the starting problems have disappeared but now I'm getting a P1132 error msg. And the it is running rougher than before (still intermittent).

Thanks.

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Wednesday, September 16th, 2009 AT 6:41 AM

JACOBANDNICKOLAS