hello guys i just did a engine swap in my 88 f150 from a 300 to a 351w fuel injected. the motor runs great and everything is hooked i believe but i am having troubles with my gauges in the cluster. the temp gauge goes higher everytime i turn the lights heater or even hit the bakes. the heater also is only working on high now wasn't like that before. the voltage gauge is all messed up always reading low even when everything is off and the oil pressure gauge is going high also when i turn everything on in the truck. now as for things i have done i have checked the alt it's putting 14.88 volts to the battery while running the battery is holding 12.50 charge while off. and i have checked the fuses under the dash and everything checks out ok the truck isn't overheating i drove it 30 miles the other day and didn't overheat. i didn't have this problem until i changed the singal wire sending until for the temp gauge i didn't use teflon on it either i grounded the gauge and turned the key on and the temp gauge went to hot so i changed the sending unit and this happen to me. any help would be great and any ideas on what to check would be great also thanks again

 

One thing often overlooked during an engine swap is grounding. The factory puts a ground wire sometimes on one of the bellhousing bolts, and it runs up and is bolted to the firewall. Make sure this is hooked up, and if you don't have one, add it in.

 

i think it bolts to the starters also if i am not mistaken it was that way when we took the 300 out and we put it back in i believe but i will check and make sure but the one i am not sure about is the engine ground where does it hook up and what to i don't think we hooked it up . i will tell you the ones that we did hook up. the one by the battery. the plug in next to the ground off the battery , the one next to the drivers side headlight. the two next to the computer and the one from the engine wiring harness to the firewall did i miss any but i am sure this is a ground issue and i hope this helps ya thanks for the help

 

Most of the v8's had the large ground wire running from the bat neg down to the front frame horn with the insulation stripped away and a metal clamp around the bare part of the wire which was bolted to the frame. It then continued on to a threaded hole on the passenger side front corner of the engine block where it was bolted to the block. This grounds the frame and the engine block, but the body mounts are rubber, so you need grounds for various parts of the body.

 

hey i will check that out i don't think it's hooked up to the engine i know where the ground the the battery is bare but it's not hooked up to the block that i am sure i am no good at wiring so where can i hook up more ground from the engine to the body? thanks for all the help i know i sound like a broken record but i just want to get my truck running lol

 

The priority for the electrical system is the starter. So the large bat + cables run from the battery to the solenoid and then to the starter. The starter case is bolted to the engine/transmission bellhousing, so the large negative wire runs from the battery negative to the engine block. All this large wiring is just for the starter.

Then you need smaller wires from the engine block to the sheetmetal. I would run a 10 gauge wire from the engine block to the firewall. Sounds like you have other smaller wires running directly from the neg of the battery to the frontend sheetmetal, so that should be ok.

 

ok i will get to checking when it warms up a little today i still got like 6 inches of snow on the ground how many grounds from the engine to the firewall would do three four? or more than that and where can i hook them on the engine? thanks again for all the help like i said before i am no good at wiring lol

 

One 10 guage ground will do, and bolt it anywhere on the engine block, just make sure to scrape the paint away on the engine and the firewall under the bolts.

 

ok will do thanks man i let you know how it turns out

 

hello again franklin i was reading my manual haynes i know not a great one but i have another question the motor i put in the truck is a 91 model motor and it call for a 5 amp fuse to run the gauge cluster and the model truck call for a 15 amp which should i got for and the 91 says it's the fuse in number 10 and the 88 says fuse 18 which in my truck as a 15 amp? should i change that fuse to a 5 amp and see what happens?

 

You have a 88 truck, and the body wiring is for a 88, so stick with the 88 specs. You had to change some of the engine harness and computer around for the v8, and possibly some of the engine harness, but the underdash and body wiring should be the same.

 

i took this whole wiring harness out of a 93 with a 351w auto and put in my standard 88 with a 91 model motor and computer from a van e250 auto but i will hook up the grounds and got a new battery ground today i will let you know how it goes thanks for all the help again i hope this works soon

 

well guys i have hooked up two new grounds from the engine block where the air pump was supposed to be and ran one 10 gauge wire to the frame and the other to the firewall where the hood ground is and i got .05 volts on that ground is that right or something wrong some where oh and the other day i was getting ready to take off and when i started the truck the starter relay switch went out and the starter just kept running so changed that and it's all better but i am not sure i can hook up both grounds starting from the same place can i do that or should i place the frame ground somewhere else and leave the engine ground to the block where it's at thanks again for all the help guys

 

well i got another problem yesterday when coming home i hit the turn signal and the red engine light came on for a few minutes and then went off i turned the wipers on and it came on again turned the lights on and off and it went off turned the heater on and it came on again.now for some reason whne i turn the heater on it will blink and go right off now this is becoming very hard to deal with i need new ideas now to see what is wrong. oh i noticed yesterday that one of the dash lights wasn't working and now it is i also noticed just now that a different one wasn't working so i put a good hit on the top of the dash and it came on so i am going to take the dash out today and see what is wrong just need some ideas on where to look other than places i have problems thanks again for all the help

 

The engine light only comes on if the computer sees a problem and has a code. If you read the codes and have none, I suspect your investigation into the dash may fix the problem.