Hello everone, I would appreciate some help on this problem. Well, here goes, this one has me stumped. I have a '90 f-150 with 5.0, auto, 4x4. When I bought the truck a few months ago it ran poorly, surged and would occasionaly die after running for a little while. I changed the fuel filter and ran a couple of cans of injector cleaner through it. After half a tank of fuel w. injector cleaner it ran great. When I was changing the fuel filter though, I noticed that whatever I spilt fuel on, like my hands, were left covered in a carmel tar substance. The fuel was clear however. Being of feeble mind the only conclusion I could come to was that maybe someone had put sugar or something into one of the tanks. Anyways, the truck ran great after that but would occasionaly run bad agoin until I ran injector cleaner in it. It seemed to alway run fine on the front tank, but when I ran the rear tank with no cleaner it would clog up after half a tank or so. Fine and dandy, I ran it on the front tank with or if I needed the rear tank I ran a couple of cans of injector cleaner through it. So far, so good. Then one day I went on a long trip (350 mi one way). Since I had run several tanks of gas through the rear I thought that it would be OK to run it without any cleaner. It was on the way down. But on the way back (while I was towing a decrepit toyota) it started to surge on the rear tank. I switched to the front tank. Unforunatly, in a rare moment of stupidity, I had not put any injector cleaner in either tank, nor had I brought any with. I limped anlong at a top speed of 40, often 20 uphill, for about 80 miles until I finaly came to the next gas station (they can be few and far between here in the Last Frontier). Anyways, a can o' injector cleaner in each tank and merrily on my way. Ran great on the rear tank after a few miles. However, ever since, my front tank has run like ****. Switch from the rear to the front, and she cuts out bad. I have been running on the rear tank since and it runs fine, but the minute it is swithched to the front tank, it cuts out bad. If the fuel pump is turned on with the key, there is plenty of pressure in the line from the rear tank, but the front tank hs only a little pressure. Of course, as of last night the rear tank started doing the same thing. Now it barely runs at all. Now, I appologize for the long tirade. I thought that the entire history might help some good samaratain help me get back on the road. My thoughts are this. Obviously it is not the injectors or anything to do with the fuel system once the tanks are joined. Is there something to do with the fuel pump in eack tank that could get clogged? Are there seperate relays for each tank? If so, where are they, what do they look like, and can they be fixed with a club and a neanderthal think tank? (Can I bypass the relay just to see if I can get pressure thataway.) I have already dropped the front tank, but the pump and sending unit is a little bit foreign to me. Anything that you can do with them, such as take apart and clean? Well, there you have it. Any help would be greatly appreciated, (such as advice on what type of truck to buy next time.)

 

I hate to use the phrase "take it to a shop", but in this case, I grudgingly would suggest it. A 15 year old fuel tank is a rusty, brittle thing, and awkward as heck to manhandle without a lift. You are liable to break fuel lines or wiring if its your first tank.... mine was a nightmare! The only internal components on the sender you can do much of anything with are the in-tank pump and the strainer sock. The strainers can get plugged as rust scale comes off the inside of the tank, and can be especially bad if you are sucking fuel from a mostly-empty tank. (All the crud settles to the bottom, where it gets sucked up against the strainer, or worse, through a torn strainer.) The relays are on the driver's inner fenderwell, and are square gray or green cubes with a bunch of terminals on the bottom. (There are a few that look alike, they use the same relay type for a lot of things under there!) You may also have an issue with the tank selector switch or the valve located on the frame rail (drivers side, more or less under the seat area), which might not be distributing voltage to the front pump when required, and now may be giving up on pulling from the rear, too..... Invest in a good shop manual like Haynes (it will come in handy, even if it doesn't help you with the fuel problem you have now), learn a little more about troubleshooting the fuel system, symptoms, and the techniques for removing the tanks and pumps, and then decide if its something you feel comfortable tackling on your own. And please be careful if you do it yourself, it can be a real hazardous mess, and we want to have you back again real soon.

 

Thanks for the response, and the info on relays, selector switch, ect.... I have the tank already off, and it is suprisingly clean inside. No signs of rust and no H2O in the bottom. Wierd, I'm not used to that. I am comftorable working on the truck, just am not used to all this technology. And I am an aircraft mechanic so as much as I hate working on cars and trucks, I hate paying other to do things I can just because I am naturaly lazy. But the things I work on are mostly designed (and all to often built) before 1950. So I really appreciate the ideas an will try the switch, valve, and relays before tearing into the in-tank pump. I will clean the strainer sock before I repalce it of course, but it really looks fine. Anyways, thanks again for the ideas.
OH, I almost forgot, I only have a Chiltons shop manual for this year ford, and am NOT impressed with the content. Are Haynes better?

 

Well there are Haynes manual, but I'm not impressed wit it either. The other option is a shop manual or Alldata. Theres a link on this site to shop manuals on cd.s The ford is about $25 but I haven't heard anyone that had gotten it.
Cheers,
Popa Tim

 

I am blessed to have a set of OEM Ford Shop Manuals on CDs and DVDs, covering my late-model stuff, and they are as good as it gets, but hard to come by (and not cheap, usually!). I have a big stack of Haynes stuff left over from my earlier vehicles, and find them a lot more detailed than the Chilton softcovers. (The annual Chilton hardcover books are more detailed, but very expensive, and aren't really cost-effective to buy for use on a specific vehicle). Nothing beats a paper copy of an OEM shop manual (I am always printing pages off the computer, and/or wishing the computer was in the shop where the tools are!), but a Haynes book is the best alternative for the "casual" wrencher. (And by that, I mean not doing it for a living, although I used to sell a lot of Haynes books to "professional" mechanics when they were in a bind!) Glad I could be of "some" help, it's what I do every day at the parts store.... try and point the customer in the (hopefully) right direction, without actually getting under their truck! TomD

 

Just a note, sugar does not mix in gas. it stays in its original form. So if sugar was put in there it would just stop at the fuel filter, or actually just complety clog your injector, if not carbruated. You can have a fuel pressure check done and see if that may be a problem. If you have to buy a new fuel pump get ready for sticker shock. its in the upwards of $250 without the float. Just my 2cents