Hi everyone,

I am new to this forum, but not to the experience...however, please forgive me if I do or say anything obviously butt-headed.

I just bought a 1991 F150 w/300 c.i. v6 and auto tranny for weekend projects (running to home depot, etc) for $500. I changed the oil, filters, etc. but have driven it very little since I bought it a month ago. It starts right up and idles and drives great (especially for 192K on the odo). Not an eyesore either.

However, the other day I started it up and I noticed a sort of high pitched whine/whir coming from the backend (near the fuel tank). I suspect this is either the fuel pump going, or maybe a leak/airhole in the line or in the tank/pump itself?

I didn't pay too much attention until yesterday when I topped off the gas tank for the first time since owning it, and noticed a strong raw fuel smell while driving home.

When I got home there was fuel leaking from underneath somewhere; either from the tank, pump, line, I dunno. Anyone have any clue? Ever hear of this?

It was not whining before the other day, so I doubt it was something the previous owner knew about, but the fuel leak I'm not so sure about. Where would you start? I don't want to put too much into it as it is just a weekend runner.

Thanks for any help,
Don

 

Guess it's time to put cardboard under leaking area, lay on it and check it out

 

You just gotta climb under there and try and see where it is coming from. The lines sometimes leak right at the fittings, but very rarely as they are all stainless steel. If you noticed it the most right after you filled up, most likely the very top of the tank has some rust holes in it. In that case just keep it below 3/4 of a tank or so until you get around to replacing the tank.

-Jon

 

Thanks for the suggestions guys. yeah, I'll probably crawl under there tonight, weather permitting. I did just buy a pump siphon from manny moe and jack to get some of the fuel out of it, guess I can top off the mowers and other cars.

Do you know, is the fuel pump under-hood, and a sending unit in the top of the tank on these? It's a single tank (aft axle), 4.9 v6. My Haynes manual doesn't go into the best detail. When did Pep Boys stop stocking Chilton?

Thanks,
Don

 

Please don't insult the 4.9 by calling it a v6; it's an inline 6.

On a single tank 91, I'm not sure if you have a 1 pump or a 2 pump setup. If it's a 1 pump, it's a high pressure pump in the tank. If it's a 2 pump, there's a low pressure pump in the tank and a high pressure pump on the framerail. There's nothing in the way of a pump under the hood.

 

:o Hey, thanks for the correction StrangeRanger, I must be braindead... I knew it was an inline 6(honest and for true!). I have a '66 mustang with an inline 200ci and was joking with friends that I bought the truck for $500 just for the motor to swap. If it looks to cost too much $$ to fix the thing I just may be tempted to do it!

If the tank has leaks, I found a used one for $85 at a salvage yard that is from the same year/motor, so I'm happy to have that covered.

As far as the pump(s), do you think the whining is a sign of impending failure?

One last question: I didn't really want my full name to appear on the posts... when I signed up I just filled in the required fields, but now I have no idea how to change it. I looked in the Control Panel but it isn't obvious how to create a "handle" for myself. Any help would really be appreciated.

Thanks, Don

 

Some fuel pumps whine for years, so I wouldn't worry about it unless you have a driveability problem.

If you have problems with the fittings on the tank, check my profile for which line tool to get. I got completely stomped on by the other line tools switching out my back tank, the one in those photos got the line off the first time!

 

I have a problem where my aux (back) tank never runs dry, nice problem until you notice that its being fed fuel by the other tank and pressurized. Thus small over flow through fill cap. I bought what sounds logical, a Control Selector Valve. Its has a elctrical plug, outlet an a series of inlets (lines are cross connected). The problem is I can't find it on the frame or anywhere so far. I dropped the back tank, its not there. Any ideas?
Roger

 

A 1990 does not have a Control Selector Valve.
You have a bad check valve in the Fuel Pump in your rear (back) tank.

 

Replaced fuel pump last weekend, $150.00 later, problem fixed.

 

Don i dont know if the tank leak is fixed but on my 93 f150 l6 4.9 308k the fuel pump mount sprung a leak where the wireing harness conects