1968dave

1998 f150 4.2 159k miles. All stock and well maintained. I was driving on highway yesterday at 60mph and it hesitated/bucked for a few seconds. It did it again a few more miles later. When I got off the highway it bucked a few more times when taking off at a green light. So, today I changed spark plugs, spark plug wires, ignition coil block and throttle body position sensor. I also cleaned throttle body as well. Fuel pump is about 4 years old. Also all parts are Motorcraft.
Started it up and now it idles bad and still bucks. I am thinking maybe fuel filter or fuel injectors?? By the way no check engine light on. Any suggestions???????

Jbrew

Right, fuel first as always. Well it's kind of a by-law. So check the pressure. I'd check now, then replace the filter and check it again. However, I don't think it's the pump, could be though.

Those models 97/98 have been known to have MEGA fuse problems. It's why Ford deleted that system and went with a split battery cable (fused) for 99 plus models.

The problem wasn't the fuse itself, rather the way Ford fastened them. Prone to cracking due to vibration or over flexing on the install. the solder ball inside the casing which joins the fuse together is what cracks.

Anyway, the problem you describe is what occurs with a cracked fuse. The fuel pump loses power intermittently and gets worse with time.

Those fuses can be difficult to check accurately since they fail under strain, bump and vibration. They are in and out.

You should check fuel pressure all the same, but your description points to one of those fuses imo...you have two.

OhioLariat

Brew: Can a 99+ cable assembly be swapped in?

Jbrew

Yes they can. They connect up pretty much the same. I have one on the 98.

EDIT: Not pretty much, they connect up identically the same without modification.

The difference has to do with separate cables entirely. The cables from the fuse box PD box under the hood and the cable from the alternator. You can either replace those with cables 4" longer or just bolt the two ends together eliminating the fuse.

OhioLariat

Thanks, I'll keep that in mind. I pulled and kept the harness from the '99 to sell.

Jbrew

Yea, if you sell to someone with a 97/98, just include the alt cable and PDB cable and they'll be all set.

OhioLariat

PDB?

Jbrew

Power Distribution Box

In other words, your fuse block or box under the hood. It houses the large main cable that powers the truck that everyone forgets about. Gets all nasty and corroded. It's out of site, out of mind. Your Battery and Alt cabling can be perfect, but if you forget to service the PDB cable under the box...your chumping yourself, -

OhioLariat

Gotcha. Didn't save that. Just the Alt and battery-to-solenoid cables.

..

1968dave

Thanks for all input. Before I read this I changed fuel filter and cleaned Mass Air Flow Sensor. All I did so far has done nothing to repair problem. I checked the fuel pump fuse under hood and it was fine, it seemed to be in tight and snug. Is the problem under the fuse box? Also a buddy of mine suggested to replace crankshaft sensor and cam shaft sensor. Could it be???? He also said to swap PCM. ????? Do PCM come programmed? I am trying to do all I can before giving up and taking it to a mechanic. I felt defeated today lol. Also still no codes. I have a code reader and nothing, no check engine light on either. thanks