I have a f-150 4.9 liter (89) with dual fuel tanks. Fuel tank number two stalls and sputters after running a maximum of two minutes on road, less then that if going up a hill or increased throttle ( it idles ok). Tank number one runs good, no hesitation or any problems. If I switch to tank number one when it sputters everything return's to normal and when I switch back to tank two the cycle repeats. Tried changing fuel filter, checked for water in gas and used fuel injection cleaner in tank. So after talking to a friend he said it could be the fuel pump in tank two or something with the tank selector assembly/delivery something (forgot exact term). I don't have a fuel pressure gauge to check fuel pressure. I know I have three fuel pumps, two low pressure pump's in tanks and a high pressure Mfi pump. My first thought is the fuel pump in tank two, but I was reading that the main function of this pump is to prevent noise and heating problems. So I need help troubleshooting this problem and would appreciate any help. Thank you and hope I haven't left anything out.

 

A couple of Qs:
Does the tank selector switch actually change to tank @2 and
Done any fuelline work that might have put an air bubble in the line?

 

This sounds typical of a recall problem they were having in some years, I want to say with with fuel pump or check valve. Search this forum for threads on dual tank problems, it's been discussed over and over. I'm having the same problem with my '95, so far they claim it's the fuel pump. We'll see.

 

>A couple of Qs:
>Does the tank selector switch actually change to tank @2 and
>Done any fuelline work that might have put an air bubble in the line?

The tank selector switch work on both tanks (draws fuel on both). As for the an air bubble in the fuel line, I don't know about that but I did change out the fuel filter to help solve my problem.

 

Because of similar symptoms i've replaced the dash switch and another truck the solenoid valve switch on the frame, but if you are definitely drawing fuel from both tanks then those aren't the prob.
Not familiar with your '98; any way the replaced fuel filter could have induced a block (air) into just the #2 tank fuel line? Prob not, and a working fuel pump in the tank shudda blown it out anyway.

Try Nat'l Highway Transportation something to look for fuel system recalls, ya' might be able to get if fixed for free & like 'Breakdown' says search around for similar threads . . .
Let us know what the fix was

 

Fuel pressure gauge is ~$40. Check it according to Haynes manual or go ahead and change the back pump. It could still be in the fuel selector valve (size of oil filter on left inside frame and has 4 lines in/2 out). They can be checked too. I priced one for '89 4.9 once for ~$80 but recently I priced one for '97 5.8 for ~$300. You can check for recalls on several Ford dealer or company websites. They said "no recall on '97".

My understanding is that sometimes fuel regulator allows too much pressure or sends to much pressure down return line and damages a check valve that prevents returned fuel from one tank entering the other tank. In case of a full tank, this could cause an overflow/fire hazard. There may be other issues or recalls though.

In the selector valve it is possible for debris to block valves or keep needles from seating. Remember Ford supplies voltage to the pump according to the dash switch. The selector valve controls the supply and return lines by pressure created by the energized pump. I don't advise taking the selector valve apart but it is easy to do. Getting it back together is difficult though. There are several small o-rings, needle valves, etc. Another issue is that thee sock filter on the bottom part of the pump may be clogged. We can't be sure though. I'd check the fuel pressure. It's not that difficult. Have you seen "check engine" light or retrieved codes?

 

I bleed my fuel pressure today using the valve on the fuel rail but that didn't help. Where can I find a cheap fuel pressure guage (efi)? I have a haynes and a chilton's manual but I don't think they say to much about the selector valve. How can I check the selector valve by the way? I wish I had a service manual, but
I'm to cheap to buy one at full price. I've checked the codes and came up with code's 33 and 77, I think. I want to go on a trip out west sometime to pick up a car and could use the extra tank.

 

I bought Innova/Equus #3640 for~$40 @ O'Reilley Auto Parts. Selector valves are tested p. 4-11The item I described is actually "dual function reservoir". Haynes Manual #36058 is really thorough and has info and tests on p. 4-15. Pull both return lines. Put hoses over res. return line ports and put in seperate calibrated one quart containers. Check the volume through both reservoir passages by switching tanks at the dash and repeating the test. If necessary perform low pressure pump tests for both pumps. Pump tests begin on p. 4-8. There is tests for regulator p. 4-9; selector valve p. 4-11; relays (electrical) and switch p. 4-17.

33 is EGR valve faultand 77 is Operator error during dynamic response test/wide open throttle not sensed. Both are common during testing and you may not have any problems. Neither will help use solve your mystery. Get the gauge and do the fuel pump test/regulator test. You may find the problem without pulling the return lines.

 

Yeah, you were right all the info's in the chilton's guide. I guess I just looked in the chilton's guide and forgot about looking in the haynes. Hope I will find the problem/problems this weekend. Thanks for your help

 

I would suspect the fuel pump in tank 2 is your problem. The tests will help verify it though. The gauge is cheaper than making a mistake. It is possible for something else to be wrong. The high pressure pump could be getting weak and would probably run better on the front tank because it's closer. I've had to change all 3 and sometimes still have problems somewhere else too. I've had better luck with '90 up though. Good luck.

 

OI Ive been down this road too often... had dual tanks most of my driving life, and never so many problems as in the last couple years. TIM is right, go ahead and test the pump, but make sure you let the pump run for a moment or two (freeflow into a coffee can or something) before you assume all is well and make the test. Even so, I would drain the tank, drop it, and replace the $5 pickup sock. The late day formulations of gasoline are unfriendly in so many ways... as it ages, it turns to diesel and water... and destroys components. I now routinely use STA-BIL in my rear tank and drain all my lawn equipment in the fall. Also, a little known resource for virtually any manual is the LIBRARY. that can save you a bundle if you work on more than one vehicle.