20 Most Recent 1991 Ford F350 - Page 9 Questions & Answers

One of your glow plugs is grounding and blowing fuse replace faulty plug

6.8L-- my info says 30--45 psi--koeo. If the spec is right in the middle, should be fine. The pressure should stay within 5 psi of that value for a minute after key is turned off. That's all I could find. Hope it helps.

Your best bet , take it to a qualified repair shop. The overdrive off light flashes is telling you that the transmission has a problem an code's are set in the transmission control module or PCM - engine computer . Speedometer an odometer not working could mean speed sensor is bad . Checking code's with a factory or professional scan tool is need . The heater fan not turning off is a seperate problem , relay stuck closed maybe . Is it running at high speed ?

need tune up bad fuel -fuel filter -cat converter - egr = and many others

Under the dash on drivers side.Make sure the key is off, and unplug the battery for good measure. Then disconnect the harness from the computer on the engine side of the firewall, it's a 10mm bolt. Then take out the kick panel inside the truck, and there's a hold down that needs to come out, it was 5/16 on my truck. Then the computer slides out towards the inside of the truck. There's a piece of rubber that surrounds the connector on the computer that will need to be transferred to the new computer. The best way I found to get the computer back in is to put the rubber grommet on the computer, then go around it with some duct tape to be able to get all sides through the opening in the firewall. It's easier when you have more than one person. Get one person to wiggle the rubber grommet on the engine side of the firewall while someone pushes on the computer from the inside of the truck. Then bolt everything back in and connect the battery

replace the oil cooler hole from stone or other road debris

Under the hood

There are power supply wires attached to the starter solenoids.When you say relays do you mean solenoids? If so the supply wires may have been attached on the wrong side of the solenoids.Other wise if you did change the relays in the fuse/relay compartment ,look under/in it for corroded wiring which is VERY common on Fords.

Do you have your fuse box and power distribution box diagrams? If so Check that a power distribution fuse is not blown out because sometimes a fuse there is a multiple connection for the passenger fuse box also the fuse blades must be cleaned to insure good contact is achieved don't just check the fuse for power and continuity you must be absolutely sure about this so you can eliminate this part/////////next it's possible that a wire/s have a corroded pin/or the wire itself from piercing the insulation to check for voltage so a continuity tester or volt meter with this option is needed here make long jumper wires to check all wires coming from the power distribution box to the bulkhead connector on the firewall leading to the passengers fuse box then the bulkhead itself to the inside fuse box trial and error is a pain but this is the only way you will find it if this is a problem cause and I'm suspicious of this also any connectors that come from the bulkhead inside that lead to the passenger fuse box //////// a lot of people make the mistake of cutting the wire insulation and then putting a piece of tape over the cut after checking a circuit this is bad news for the future of that wire because the copper corrodes after long term exposure to the air eventually eating the wire and breaking the continuity of the wire/circuit and now here you are going crazy trying to find what should've never happened in the first place make sure that if you have to find continuity by cutting insulation of the wire that you then cut and solder the wire and heat shrink it and this kind of stuff won't happen I'm just giving you all the possibilities here to help you get through it and find the problem you've already checked the fuse and you said it's dead so it's not the HEC/HIGH ENERGY CLUSTER INSTRUMENT PANEL THAT'S A PROBLEM HERE IT'S FROM THE UNDERWOOD CONNECTIONS TO INSIDE GOOD LUCK AND IF YOU DON'T HAVE YOUR DIAGRAMS GO TO FORD OWNERS MANUAL.COM AND REGISTER FOR FREE THEN DOWNLOAD YOUR OWNERS MANUAL GO TO ROADSIDE EMERGENCIES AND YOUR FUSE BOX DIAGRAMS ARE IN THERE AND OTHER INFORMATION ABOUT YOUR TRUCK YOU CAN KEEP IT ON YOUR PHONE/COMPUTER AND PRINTOUT ANYTHING TO MAKE IT EASIER TO LOOK AT ALSO CAN YOU TELL ME YOUR ENGINE SIZE I HAVE A 2000 TOWN CAR WIRING DIAGRAM AND A FORD CROWN VICTORIA 2005 AND SOMETIMES THERE THE SAME.? BUT YOU CAN FIND WHAT'S' WRONG BY SEARCHING YOURSELF THE WIRES AND INTERNET FOR DIAGRAMS BUT IT'S' A SHOT IN THE DARK GOOD LUCK STEPHEN

You might try Helm Publishing in Highland Park Michigan. Some of the manuals like you are missing had a page at the end of the book with addresses such as Helm. I do not know if Ford Customer Service at Corporate level would have more info. It seems to be a trend for resale places to toss out manuals like you need.

I recently tried the DIY service and repair manuals from a website and it actually helped me repair transmission problem in my jcb 3cx site-master. It would'nt move forward or reverse, engine was good both solenoids for forward and reverse worked, but still couldn't diagnose the problem. I don't have much technical knowledge but I just followed it step-wise, and now it works perfect! covers wiring, codes, diagrams, torque specs, PCV, everything got it from www.reliable-store.com

Wiring, schematic, electrical diagrams, fuse diag, error codes etc are basic contents of these online books they have here on this website www.reliable-store.com I have attached. Must check it out

These engines are known for their problems with the variable valve timing mechanisms. First thing is to make sure you're using the right weight oil because the mechanism depends on oil pressure to change valve timing. If using the wrong viscosity, you screw up the valve timing. Also, neglecting oil changes can do the same thing. So can sludge buildup. Remove the VVT solenoids and check for clogged solenoid screens. None of the symptoms or codes you listed point to a bad computer. They all point to a problem with variable valve timing.

All kinds of repair manuals are available here.Have a look of this may be you will get something useful. Best Manuals

My first guess would be that you have a vacuum leak. If you have a V8 the lose of power may not be felt in the two first gears, but becomes more prominent in the two last gears because the RPMs have gone down. First check at your brake booster, and then move to other hoses in your engine compartment. Good Luck Friend.

Did you know water and electricity don't do good things. You could have shorted or damaged any number of plugs or wire connection. Have to see if your getting power to starter relays. May have one or more bad connections to repair