Hard start under 1/2 tank. Replaced a lot of parts!!

[Big Del]

Hi new to Oil Burners, converted from a powerstroke forum.

My truck is a 90 7.3, it won't start under 1/2, the closer it gets to half a tank the longer it cranks before starting. When I get it started its fine the rest of the day. It will run the tank empty if I'm on a road trip with out any direvability issues but if it sat over night that low it won't start.

I did a cup, return line and O ring kit and it didn't fix a thing. I dropped both tanks and the tanks and pickups were in perfect shape, so were the hoses return and supply. The lines to the sending units were hard to see and the clips were brittle and the tabs were broken so I put new plastic keepers on thinking-hoping that would fix the air intrusion... NO GO. The other reason I dropped the rear tank is it has had a fuel leak from the top of the tank for years and I have just ran off the front tank with no problems. So I thought I would pull it and check everything out, that is when I found the broken clips, thought maybe that was it, put it all back together put fuel in it and the top of the tank still leaks. I'm getting frustrated filling it everytime it gets close to half.

I also put new fuel filter with petcock, pickup pump and I don't see any visible fuel leaks? IP is 4-5 yrs old with maybe 20K


Thanks lengthy first post ;p

 

[Big Del]

Searched for a couple more hrs, so see if I'm missing something simple... hoepfully. I have repalced the fuelfilter numerous times, but what are these fuel heater Orings I read about? I don't see anywhere to replace these orings?

 

[jonathan]

look it the tech area

 

[flareside_thun]

There is an excellent write-up in the tech section, at the top of this forum page, about the fuel heater o-ring replacement process.

 

[Agnem]

You are a good candidate to convert to an electric fuel pump. Sure will help you troubleshoot this problem.

 

[Big Del]

There is an excellent write-up in the tech section, at the top of this forum page, about the fuel heater o-ring replacement process.

Thank you that is a great right up, I used the part number and have the o ring ordered..

You are a good candidate to convert to an electric fuel pump. Sure will help you troubleshoot this problem.

I'm wondering that, at this point it could still be anything. Is there any good writeups on electric pump installs?

 

[Big Del]

I called the local IH dealer back and tried to order the fuel check valve. The parts guy said it showed two options, continous flow or non continous flow? I don't know wich one it takes and he has to order either one. I don't want to pull it for sample and have it down a cople days waiting on the part. Any idea's or a PN.

Thanks Del

 

[rustnsuch]

fuel tank switch valve ??????

 

[Big Del]

fuel tank switch valve ??????

I was wondering if the fuel selector switch could be part of the problem? I put a new starter in it last night as I noticed it was starting to drag. Man that thing cranks fast now, like a whole new truck. It's just crazy with the tank of Full it pops off with in two revolutions even at 20*. You would think the 1/2 tank problem would be noticable with a wet fitting or something. I really have no idea and I hate throwing parts...

 

[rustnsuch]

I was wondering if the fuel selector switch could be part of the problem? I put a new starter in it last night as I noticed it was starting to drag. Man that thing cranks fast now, like a whole new truck. It's just crazy with the tank of Full it pops off with in two revolutions even at 20*. You would think the 1/2 tank problem would be noticable with a wet fitting or something. I really have no idea and I hate throwing parts...

I've got a friend that just had a similar problem that drove us nuts. It was the fuel tank switch valve.

 

[Big Del]

At 212 bucks I'm going to figure out how to bypass it for test purposes..

 

[flareside_thun]

The selector valve on Rock Auto is 105 bucks at most......