I bought my truck about 8 months ago and i have a few guages not working right. My tach goes to zero at a stop light or idle but when i hold the brake and touch the foot feed it raps it up a little to normal.. My fuel guage doesnt work correctly either. When i hit 1/4 tank it's acctually empty. ( it holds almost 16 gallons at 1/4 tank). Anybody ever seen either of these problems? Also i replaced my dimmer switch on the floor about 7 months ago because when i switch to brights it kills the lights. only dims worked. It worked great for a little while but is doing it again. Sometimes lights wont come on at all unless i stomp on it a few times..Ground issue? Thanks in advance for any advice or info! By the way it is a 1991 F250 Reg Cab 7.3 IDI with the E4OD.

 

Most likely you need to replace the tach sender on your truck to fix the funky tach. Does the tranny ever shift funny?? As for the tank, it sounds like your pickup is broke off. Cant help ya on the dimmer switch.

 

My truck is a 1987 F250 excab with the 6.9. When I brought my truck home I didn't know anything about it so I learned a lot the first week. The oil pressure gage started about the high side of the N and as it got hotter the gage went almost to the bottom of the gage so I always thought I didn't have any pressure by the end of the day. The water gage was ok when I first bought the truck but that's another story. The volt meter has always looked ok. The front gas gage registered full till it gets almost to the 1/4 mark and then drops like a rock. The back tank gage is pretty close to on the mark. I did find out I can drive both the front and back tank till the needle is on the red. One thing I learned is the oil pressure and water temp gages are good for guessing as is the gas gage. The best thing I would tell you is to buy an after market gage for the oil pressure and water temp gages. Then you'll find out what is really happening. I can't tell you much about the tach as mine doesn't work. I replaced the sending unit on mine but it still doesn't work. The sending unit is on the housing toward the drivers side where you put in the oil. Sounds like the dimmer switch has a short.

 

The off shore parts (dimmer switch) leaves a lot to be desired.

I have to change mine about every other year.

Sounds like the float arm is bent, but that is a drop the tank and pull the sender to rebend the float arm repair.

Probably the tach sender, look and see if you can see bare wire on the leads where they come out of the sender.

 

my tach did the same thing and a new tach sensor fixed it.

 

Thank you guys so much for the help. One other stupid thing is that my dome map lights with the switches on them don't work in my truck...which is weird because in the donor truck it worked perfect, got it in my truck and nothing...i'm gonna try to figure this out tomorrow. any tips are appreciated! Thanks again guys!

 

dave is that one of my pictures?lol i am the only one that does that white blocks that i know of.because i have no idea how to edit pics like you guys

 

how do the float arms get bent? mine does the same thing im empty on a quarter tank but how many liters does the front tank hold ? im wondering if my pick up is broken off as well because on empty i can only fit at most 50 $ (almost a doller a liter here) and by the size of the tank i would think it would maybe take more...

 

when mine did this it was because i "accidently"pulled the indicator off the gauge.so i just filled it up and pulled the indicator off and reset it to the full mark.that was my fix maybe it could be that easy for you as well.just watch your mileage as a fail safe if you give it a shot

 

well when im full it reads past full now ... so not sure whats going on i guess i could just drop the tank but i just need my cash flow to catch up with me before i start taking things apart

 

i would give my trick a go.it will only take you 10 minutes or so all you beed is a torx bit to take the clear cover over the gauges off the black trim just pulls off.so just take the dash bezel off and 6 screws out pull the needle off and reset it with a full tank.put it all back together and see what happens

 

ha ha my cover is off now i cracked it cleaning it and i think i remember trying to pull the needle off and i dont think it would come off...

 

that probably caused your issue then.i actually have another gauge if i can find it i can send it to ya if you need it.but i do remember mine came off fairly hard

 

The best two ways I can think of for the float arm to get bent is someone with a siphon hose or the tank has had the sender replaced and they bent it either in shipping or during installation.

When I change mine, I always adjust it so when the gauge reads E the engine is sputtering.

But I do have an unfair advantage, I just raise the dump bed and can get to both senders.

 

I have an issue with my fuel guage every once in awhile it wont rise from E when i know its around 3/4 and the gp light doesnt come on at the same time but if i top it off with fuel it starts working properly again. Oh and my rear tank wont accept fuel! i know its round 1/4 tank and the neck just fills up and drains in SLOWLY what is that all about