20 Most Recent 1991 Ford F150 Questions & Answers

Sounds like stuck floats to me. Unless they are actual sensors. In that case they are not reading correctly. And therefore should be replaced. Unfortunately either way I think you are going to have to pull the tanks. Not a fun job at all. If you have an OBDII and I think you do. Go to our local parts store and they can hook up to it and pull fault codes from the ECM (electronic Control Module). You might get lucky and it will tell you what is wrong. If that doesn't work out for you. Consult with Ford, either online or at the dealer. They might be able to steer you in the right direction. Probably try to steer you into one of the repair bays. But you stay strong, resist the service person. You can do this, I believe in you! Well I know I can do it. Therefore I believe you can too!
Good luck,

1991 Ford F150 | Answered on May 17, 2019

Are the plugs wet yes/no? If so what is it antifreeze or water also knowing what kind of car it is will help a lot because of the design but if it's antifreeze and a 4.6 engine the thermostat/crossover gasket is leaking and antifreeze is running down the heads and into the spark plugs chambers on either engine bank this is provided that you are using antifreeze in your radiator if it's water same thing if your using it to cool the motor but if not and water is present the inner fender splash guards are missing and big puddles of water when hit will splash the water inwards towards the engine and will run into the cylinders also high pressure car wash will do it look at your coil on plug boots if no moisture is there they could be soft or cracked and the positive coil firing voltage is jumping to ground and is not firing the plug/s involved and they should be blackened with soot smell the plugs and feel the metal casings if slippery there's antifreeze if just wet water none of the conditions described are present change the mass air flow sensor and I almost forgot to tell you to bend the spark plug boots back and forth if the are bad they will break and also roll them in your fingers looking for brittleness and cracks also you may have a bad batch of gasoline in your tank check all above first and open the throttle body plate with your fingers if it's very black inside a good cleaning with Berrymans fuel injection cleaner and a change to higher octane brand name gas will correct this and I'm not there so if your using delta,valero,usa liberty or any other garbage fuel this is a indication of why your having the problem there's no detergents in those fuels and they are made from the crud at the bottom after the name brands have been refined and the higher the octane rating the more stable the fuel burns but the junk fuels burn very quickly and varnish build up is eminent in the cylinders your injectors and your throttle body the junk fuels make it build up at least 3 times faster than higher quality fuels and there's no detergent helping to keep things clean so if you think that saving 10 cents a gallon is worth the cost of replacing injectors or other components plus labor maybe $600-$800 think again and if a tow is involved well I guess you've hit the jack pot oh boy 3am on the side of the road good luck a taxi mechanic here in nyc 50+ years of repairs and motors with 450,000 and still running is where this came from and next time give your specifics on the vehicle my genies on vacation and the crystal balls still on loan from new years in Times Square but I tried my best good luck stephen

1991 Ford F150 | Answered on Jan 26, 2019

Check your fuel selector valve for proper working condition. The internal valve may be stuck.

1991 Ford F150 | Answered on Oct 03, 2018

On this one, You will need to know where the water is leaking from and oil as well. Sounds like a hose or Tstat gasket. The oil leak cud be the gasket on the oil filter.

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1991 Ford F150 | Answered on Feb 21, 2018

Wire that doesn't test as bright could have frayed wire/short or fuel pump may be bad.

1991 Ford F150 | Answered on Feb 12, 2018

unlikely to have 2 filters as it will have only one line from the operating tank

1991 Ford F150 | Answered on Jan 28, 2018

likely to be a flat battery. try starting using jump leads from another vehicle. possible you have a faulty alternator not keeping battery charged or something is draining battery when engine off

1991 Ford F150 | Answered on Jan 20, 2018

Check dash gauges. Are they stepper motor type. Check internet for repair service if so. Around $125

1991 Ford F150 | Answered on Jan 10, 2018

Sounds to me like you have a broken linkage from your ignition tumbler to your ignition switch. It is a plastic "arm" that pushs.pulls a metal tab on your ignition switch.

1991 Ford F150 | Answered on Nov 20, 2017

Look in t he fuse box lid under the hood. It should have a diagram of the location of the relay.

1991 Ford F150 | Answered on Oct 28, 2017

Did you change out the fuel filter's?Are fuel injectors clogged.

1991 Ford F150 | Answered on Aug 17, 2017

Are you getting power to the coil? If coil voltage is low, suspect the radio capacitor is shorted. If the voltage is good, the problem may be the ignition module. One other possibility is a problem with the distributor pickup coil or connector. See 2nd page at link below.

1991 Ford F150 | Answered on Aug 02, 2017

Well furst of all fix the leak before you have a fire.

1991 Ford F150 | Answered on Aug 02, 2017

Check the bulb. The problem has to be right there at the socket for the left rear. You do understand how the two filament bulbs work? The brake and turns use one filament, while the park lights use the smaller , less bright filament. And the bulb has two buttons on the bottom that touch two buttons in the socket. That is how the current is carried separate for the two lights.
It sounds like your bulb is wrong, or the socket itself is compromised.

1991 Ford F150 | Answered on Jul 27, 2017

You need to do an EEC IV engine control system fault code test, you can do that without special tools by following the instructions at the link below. EEC IV Self Test Ford Fuel Injection and EEC IV Electronic Engine Control...

1991 Ford F150 | Answered on Jul 25, 2017

You might want to check for a busted fuel pressure regulator diaphragm. With the engine running, pull the vacuum line off the regulator. If gas comes out of the regulator, replace it. For the acceleration issue, check the signal on the map sensor. It should change drastically when you open the throttle.

1991 Ford F150 | Answered on Jun 17, 2017

Did you also change the Coolant Temperature Sensor? If it is reading wrong, the computer may not realize the engine is cold, and won't increase the gas for that.
Spray some carb cleaner around the outside of the throttle shaft, if engine speed increases, that could be a vacuum leak. I've never heard of that, but anything is possible. It sounds like it would have to be a serious air or vacuum leak to cause your problem. Have you blocked off the power brake booster to check if that is leaking?

You might want to do a compression test to see if there is any internal mechanical damage.

1991 Ford F150 | Answered on Jun 09, 2017

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