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Stuttering Ford F-150

Dear Tom and Ray,

I have a 1994 Ford F-150 pickup with a 4.9 litre fuel injected inline six. Truck ran fine and took me to my destination but after sitting for 4 hours the truck would not start. Engione would tur over normally and could hear fuel pump running(didnt seem to stop) but truck would not start.

I changed fuel filter but truck would still not start. I removed air filter assembly and poured starting fluid in the air intake and engine started but idled roughly. Engine will rev up but runs very rough and lacks power when driven. Also th check engine light stays on.

Would appreciate any input as t what would cause the problem and what a possinle fix could be.

Many thanks,
Lou

I don’t think Tom and Ray are users on this forum.

I’d start by measuring the fuel pressure.

Pull the code and post it here.

Post the codes, please.

TBI or EFI?

Check the timing chain for wear.

Tester

There has never been a TBI 4.9L…nor a timing chain. There is a composite CAM gear that can lose a few teeth after a spell. Sounds like the timing gear may have jumped. No biggie. Just replace it.

That truck has a 2 stage fuel pump and hearing one pump, or even both pumps operating does not indicate that fuel pressure is adequate. I would suggest that you test for adequate fuel pressure. Because the engine will run, albeit poorly, indicates that the pickup pump in the tank is functioning but if fuel pressure is not 40+psi with new filters the high pressure pump is failing. The high pressure pump is on the frame rail under the cab.

PLEASE EXCUSE ME. The 1994 model F-150 had no rail mounted fuel pump. The in tank pump was the only pump on that truck. But it would be advisable to test for adequate pressure. The testing procedure includes testing the pressure regulator which might be at fault.

No timing chain? I wonder why they sell them for the 1994 Ford 4.9L here?http://www.partsgeek.com/catalog/1994/ford/f150/engine_mechanical/timing_chain.html

Tester

The 240 and 300 cubic inch Ford I-6 engines were famous for their longevity and the timing gear was one of the bullet proof features of the engines. As for listing a chain on that web site, I find that many parts suppliers list generic parts that fit engines with any similarity to the one specified in the search. A Holley universal electric fuel pump is often listed for any application, carburetor or electronic fuel injection on one site that I often check.

@Tester,

Please note that the timing chain is listed as fitting only 5.0 V8 and 5.8 V8 applications.

Oops…one of the 4 brands sold lists the 4.9…the others don’t. However, having owned a 4.9l Ford six, I assure you they use gears.

Those engines never had chains and the weakest link is the Cam gear…they do lose teeth and are more troublesome(failure frequency) than the small block chains…believe it or not. Many people just put a steel gear in as a replacement… No timing chain would ever go in there w/o a lot of silly rework. All of those engines were always free-wheeling, non-interference.

DO NOT hammer the new gear on the shaft. It must be heated to about 300F and put on quickly (keyed, press-fit).

I have repaired one timing gear failure on a 300 Ford engine in 30 years of fleet work with a great many of those engines in the lineup. My experience was that the cam gear failed, wiped out by the metal crank gear and stopped turning all together, the crank gear was spinning in the gap chopped out of the cam gear. Such failures seemed rare to me. I rebuilt those engines and saw them run 200,000+ miles in commercial delivery and service fleets. I have owned several Ford 300s and currently own an F-150 with that engine.

I would pull the codes first and go from there. This truck should be a TFI model so those modules are always a suspect too.

My experience is also extensive those. UPS seemed to eat through them back around '93 at around 80K miles. Ford also had run of blocks that failed to get the rear cam bearing oil drain hole drilled which effectively turnd that back of the cam into a pressureized cylinder that caused the cam to bore its way though the thrust plate and through the timing cover. I had the pleasure of correcting several of those. The cam gear issue was well-know in our shop and often resulted in a running, powerless engine that would fool folks on compression testing into thinking they needed a valve job… Anyhow, fairly easy job to do if presents itself as being necessary.