starts,wont start...cantfind first post

[Jim @ Fran]

broke down inboseman mt..ranfine all day and after stopping to check in, it would turnover but seemed likeno fuel...1993 ford coachman with 460 cu..Jim Godward suggested Motor coachmaint in belgrade...the mhstarted right up in the morning and we tookit to them...very nice peoplethere...spent almost 2 hours tryingto diagnose what was wrong and couldnt find anything wrong??
175.00 later they saidthe only thing they could figure it could be was the fuel pump...the DW decided new fuel pump so we did that..totalbill was 572.00.......2 days later it did the samething .....

question.....there seems to be a suction when I unscrew the gas cap after driving for a long way....is that normal????    thinking vapor lockor something like that might be the problem??  thought the cap was supposedto be vented so no pressure in the tank...

Help....and many thanks...

 

[Gary RV_Wizard]

Yes, the tank should be vented and a lack of venting would be consistent with the problem you had. You may have an incorrect fuel filler cap (no vent), or perhaps there is a separate vent tube that is blocked, possibly with fuel in a low spot in the line.

A Ford dealer or NAPA store could probably help with identifying the correct type of filler cap. If the fuel tank does not have a seprate vent tube, then the cap itself must have a vent n it.

 

[Jim @ Fran]

The mechanic, Scott said he couldnt find a vent on the fuel tank....the fuel cap looks orig by its color and wear etc...it is a locking cap and key looks like all the others...looks like it has vents etc in it....if the suction is not correct think I will try another cap...
cap looks clean etc but suppose it could be plugged....and a lot cheaper than fuel pump....dw not too happy..Thanks for input Gary

 

[SargeW]

Unfortunately you would not be the first person to pay a huge repair bill only to find out that their gas cap has failed and is no longer allowing air into the tank. It's not real common, but it does happen.

The vehicle will start up after sitting because over night air has had a chance to seep back into the tank. Then when the vacuum builds up in the tank the problem reoccurs.

 

[Jim @ Fran]

exactly what is happening...wish the mechanic would have told me that....Thanks to all....

 

[Howard R]

Assuming it will do it to you again ... for troubleshooting, try removing the gas cap and see if it will start then ...

Howard

 

[Jim @ Fran]

did that...also in researching new gas caps they allseem to have a pressure release which would indicate that they dont actually vent when on tight...just whenyou either turn the key or push the pressure releasebutton....back to square one...there must be a vent somewhere by the tank...the mechanic that checked it out was not able to locate one...maybe there never was one.. does anyone know a site where i can ask what was original equipment on a 1993 econoline with a 460 ford/??  Thanks

 

[RVRAC]

This is where I go for this kind of stuff.  www.rockauto.com

They are very helpful.

 

[ironrat]

Went through this with my old MH with the 460 Ford. There are three different type vented gas caps. Emissions wise you can not have a vented cap that vents to the out side. So the cap needed is one that in vented in and sealed going out. Some will vent out and not in! The old style vented caps vent both ways in and out and some are just sealed completely. Hope that makes sense to you, but again the Ford system needs to vent in but not out.

 

[donn]

did that...also in researching new gas caps they allseem to have a pressure release which would indicate that they dont actually vent when on tight...just whenyou either turn the key or push the pressure releasebutton....back to square one...there must be a vent somewhere by the tank...the mechanic that checked it out was not able to locate one...maybe there never was one.. does anyone know a site where i can ask what was original equipment on a 1993 econoline with a 460 ford/??  Thanks

You have a in tank fuel pump/filter assembly.  I would definitely suspect that the filter is clogged or that the pump or pickup is gone south.  Either way it will necessitate dropping the tank to find out for sure.  when i found out how expensive the intank unit was from Ford years ago I opted to get rid of all of it and installed an external fuel pump and filter assembly.  No more problems.

 

[Alfa38User]

In trucks of that vintage are the gas tanks not (out) vented to a charcoal canister up by the engine?? This would indicate a tubing system heading from the tank area to the canister at least. Fumes from there are usually drawn into the combustion system.

Next time it fails like this, the simple fix would be to loosen the cap. If it then starts you have your answer. But... you may also have a weak pump and Fords of that era were well known for pump problems.

 

[ironrat]

In trucks of that vintage are the gas tanks not (out) vented to a charcoal canister up by the engine?? This would indicate a tubing system heading from the tank area to the canister at least. Fumes from there are usually drawn into the combustion system.

Next time it fails like this, the simple fix would be to loosen the cap. If it then starts you have your answer. But... you may also have a weak pump and Fords of that era were well known for pump problems.

You are correct the tanks are vented to a charcol canister, that is why the cap is vented in to allow air in to replace the used fuel but closed to the atmosphere as the fumes are suppose to be drawn in to the engine via the charcol canister and by way of engine vaccum.

 

[Jim @ Fran]

we hadthe fuel pump replaced.....mechanic said he could not find any vent....when this first happened I immediately thought of some kindof vapor lock and removed the gas cap...no  good...however after leaving it for a couple hours it started right up....think I willhave to talk to Ford somehow....

 

[carson]

My unsolved mystery.... What causes a VAPOR LOCK ? Overheated gas line perhaps ?

  As compared to a vacuum related problem. If the tank is not ventilated it should be obvious that gas will cease flowing. Now then, on a lot of cars the 'Check engine light' will come on if you leave the gas cap off by mistake. Hence the mystery. What gives ? Guess I need to be educated.

  (Not intended this to be a hi-jack thread).

 

[Jim @ Fran]

Thought  about this all day driving...now in sidney, ne.....if the gas cap is vented to let air in but not out, then there shouldnt be any pressure on it when you unscrew it to fuel?????  mine sounds like I am opening a can of soda when I take it off..

thanks for any help on this....

 

[ironrat]

Thought  about this all day driving...now in sidney, ne.....if the gas cap is vented to let air in but not out, then there shouldnt be any pressure on it when you unscrew it to fuel?????  mine sounds like I am opening a can of soda when I take it off..

thanks for any help on this....

Think about this, does your car do this? Something in your system is not doing it;s job correctly.

 

[SantaCruzRider]

I had an issue that sounds identical on my '94 Ford 460. Would run fine all morning then stall out and was close to impossible to start without an hour or 2 of rest and cooling off.
Common conditions were: altitude above 6k', outside temps in the 80s+, mid day or later and after several hours of driving, and most often while we were climbing.
Remedy (hopefully - though we have yet to repeat the above conditions) was new in-tank fuel pump (mine was WAY pricier than yours, so it's probably gem-encrusted), new EGR valve and new oxygen sensors.
Good luck with your fix.
Dan

 

[Jim @ Fran]

Thx...When we ran for a few hours and then stopped for fuel it always started right up after filling...the only time it wouldnt was when we would stop and not fuel and then start....in talking to local mechanics etc they feel its more than likely a fuel line somewhere near an exhaust pipe or heat source that warms up the fuel enough to cause a temporary "vapor lock".....anyway since we decided to either fuel up and then get a campsite or just get a campsite and then shut it down for the night we have had no repeat of the problem....leaving in a few minutes for "UP North" Wisconsin for a week or two to catch the last 2 weeks of golf and beautiful color and then putting the rig away for the winter....