1970 f-100 390fe.Truck quit on the highway today, checked carb. no gas comes out. Got under truck took rubber connection hose lose no gas flow. Blow on fuel fill inlet gas flows from rubber hose. Hook up rubber hose check carb bowl, empty. Fill up bowl truck starts and get home no problems.

Go out tonight same problem. Same routine only this time gas does not keep flowing. Disconnect rubber hose no gas, blow on fuel fill inlet gas flows good for a few seconds then stops. Blow on inlet again gas flows good for a few seconds and quits again. Seems like the gas should keep flowing? Does it need suction from fuel pump to keep flow? Not far from home so I fill bowl till it quits. Get out fill bowl again till I get home.

This is my third pump in just over a year. Between last 2 pump replacements I cleaned out lines, gas tank twice, replaced all rubber hoses and filter. Every time problem got this bad replaced fuel pump and problem solve till pump / problem comes back.

Tomorrow I'am going to hook up a gas can before the pump and see if truck will keep running. Any thoughts as to what is going on? Thanks.

 

[QUOTE=70-360fe;14083533]1970 f-100 390fe.Truck quit on the highway
This is my third pump in just over a year. Between last 2 pump replacements I cleaned out lines, gas tank twice, replaced all rubber hoses and filter. Every time problem got this bad replaced fuel pump and problem solve till pump / problem comes back.
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Maybe it's time to install a back up electric pump like a few of us has done.
These little pumps are a flow through so it don't effect the manual pump pull of gas. These will help push gas to your manual one.. I'm some day going to ad another tank so I have a tank switching valve inline with mine..
orich
http://i103.photobucket.com/albums/m...ithshutoff.jpg

 

Maybe check your tank vent line for blockage or install a vented cap. Just a thought.

 

Sounds like rust & crap in the tank, that happened to me a lot. I added an electric pump on mine as orich suggested below to help overcome the problem. You could hear the pump operating normally and then sometimes you'd hear it having to work much harder (sounds "dry" as in when its priming itself). The electric pump did help a lot but ultimately I fixed it correctly by replacing the tank, after which you could hardly ever hear the electric pump even come on.

 

Your problem is more than likely crap in the tank, your gonna have to take out the sender and take a look around, then clean it out.

On a lighter note, I had a 68 f-250 4x4 back in the day that I bought super cheap because it would run perfect for a week or so then die stone dead. He had it to several shops and nobody could figure it out.

I had it for a month before it happened the first time, and I did the same routine as you out on the hyway and got it home, when I opened the tank, turned out, somebody had used clear silicone to seal the sending unit oring at some point, they used too much and a snake about 4" long got severed when he installed it and it was floating in the tank, the pickup tube didn't have a screen so the snake would float around for awhile until it found the pickup tube and get stuck there, if you left it alone long enough to tow it to a shop it would slide back out. easiest fix I ever had.

 

Cleaned out tank twice in the past year, even rolled it around with rocks in it to get out any rust. I will check it again if called for. I don't think my 70 has a vent tube just a gas tube. I have seen other trucks that more then one tube come off gas sending unit, mine has only one. (Not sure if they were for extra gas tank or venting) I though it might be the cap so I try running with the cap off, no difference.

I find it strange that gas won't keep flowing from tube coming off sending unit. If I disconnect the rubber hose from metal line blow into gas tank it flows good but only for a few seconds. I know tube goes to the bottom of the tank but the other is lower than the tank? I'am going to check that metal line as best I can and try to run something thur it to clean it out. I think maybe that's where the problem is or the pump has gotten weak and does not have enough suction to keep gas flowing. (Cheap donkey after market crap) Maybe an air leak somewhere from tank to rubber hose connection? (rubber connection hose was replaced in past year)

Please tell me more about electric pump back up. Is this a replacement for mechanical pump. Please tell me about your set up's, brand if you use a fuel reg. etc. If I go that route I would prefer to get one from a brick and mortar store as I need to get this thing up and running again.

Going out to do some checks in a few, will report back my finds. Thanks for the suggestions!

Looking at these.

http://shop.advanceautoparts.com/web...p2HomeClicked=

Or keep mechanical and add this.

http://www.autozone.com/autozone/acc...fier=732036_0_

 

The Holley is a little over kill for a daily plus you'll need a regular to keep from flooding most likely. I'd go with Mr Gasket one.

Have you hand tested the pump after removing it?, By working the pump arm lever that ride on the offset wheel that is bolted onto the timing gear to see if is still working?

This wheel wears down just enough to not work the pump over yrs of use.
This sounds like what's going on since you have gone through so many in the last few yrs.
Their is a repair kit when this wheel wear down to much..
orich

 

I'am going out to remove pump now. I do have the last pump that I though when bad but seemed good after removal. Change it away and fix problem till now. Do you have a link for the repair kit? Thanks!

 

While it would be a good idea to check the fuel system I think your problem is new old stock fuel pumps. The rubber diaphragms built in pumps before we got the current Oxygenated gas can't handle said gas. It makes them fail. I'd check the sock on the fuel sender and blow some compressed air through the line but it's probably the pump. Prolly about 8 months ago there were a bunch of us that had NAPA brand pumps fail on us.

 

Most online auto parts stores sell the FUEL PUMP ECCENTRIC Or look on ebay.
Rock auto did sell them at one time...orich

 

Have you ever ran electric by itself? Why not? I pulled my pump off cause the pin on my new can didn't extend enough to fit in the eccentric. Would be a pita to install manual pump back but I am using an old Bendix unit my dad had laying around nos.

 

Bought first pump from napa lasted a month. Got new one from napa lasted about 8 months. Next came from autozone about 3 months ago and now it's bad. All 3 where airtex pumps. I have the last one from napa and the autozone one off, both work but seem a little weak. Should I try another higher quality brand? Really don't like electric fuel pumps but if that's what it takes.

Checked out lines by blowing on them but have not blown compressed air thur them yet. All lines seem clog free tank to carb. Really think pump is bad/weak.

I'am going to hook up pumps to tank and work pump by hand to see if I get any draw.

 

Have you checked the draw tube in the tank for unwanted debris or rust holes?

 

I hooked up pump to rubber connection off metal gas tank line and pumps gas by hand. Did some research and I think the problem is with the pump drive. Pushed on the timing chain with finger thur pump hole chain moves a 1/2inch at least. Look like it's time to replace timing chain. I have never done one but read up on it and does not seem to hard. So thoughts - suggestions.

All tubes look good the only one I can't visually check is the inside draw tube. Blow on it and I can hear gas bubbling so I assume no holes/leaks.

Just did vacuum test on both pumps and getting about 7 to 8 psi.

 

Make sure Engine at TDC with the #1 cylinder on it's compression stroke. Use a puller to remove the vibration damper. The marks on the 2 gears should face each other. Cam gear mark at 6 o'clock and crank gear mark at 12 o'clock. I use an installer tool to press the vibration damper back on.