RANT: Truck starts then dies - fuel system air intrusion

[jim x 3]

List:

I have tested my GPC and GPs - all are good. Normal GPC behavior either cold or hot. New starter (3 mos.) and new batteries (1 week), so I have good GP and starting power.

After a long idle period, like overnight, the truck starts normally like it would cold then immediately dies. Then continued cranking (8-10 seconds or so) is needed to restart. The engine sputters a bit when it does start, then evens out and runs normally. So I have the oft reported air intrusion fuel leakback problem. There are no visible fuel leaks anywhere. This is, of course, nothing new to any of you here.

FLAME ON:

I'd just like to know why the fuel system in these trucks is so fragile. I have two other diesels, a Mercedes and a Toyota. The Toyota is 7 years older than my Ford and the Mercedes is 8 years older. I have never had a problem with the Toyotas fuel system. The Mercedes has had the rubber injector to injector return lines changed - that's all (there is no plastic, the injectors themselves have integral metal barbed fittings). The injector-injector return lines on the Toyota are all metal - no POS plastic or rubber at all. And no "olives" anywhere either. So why couldn't Ford design and build a much more robust fuel system? The Germans and Japanese sure could!

FLAME OFF.

Regards,

 

[Brad S.]

Get rid of the olives.
Not sure what type of fitting goes into the mech. fuel pump, but I put one in that had a hose barb "output", then put a fitting on the inlet side of the fuel filter, that had similar hose barb fitting, then a piece of 3/8 rubber fuel line between.
On the outlet side of the fuel filter put a 3/8 npt with a 3/8 compression male fitting. On the IP the brass fitting is a 3/8 compression fitting as well.
I use a stainless steel water facuet line that has 3/8 female compression fittings on both ends.
The SS water facuet line is completely stainless on the inside, no coatings to flake off.
There have been some other combinations, keep on researching & reading.

 

[bbjordan]

Time for an electric fuel pump?

 

[Ataylor]

I agree with the fact that the plastic return caps and the olives are a weak point in the system. I replaced the caps and o-rings twice with good quality kits only to have two different caps start to leak. I made sure I trimmed any flashing off the caps and used new o-rings each time with lube. The leak wasn't a drip or even wet, but I could see the tale tell dust accumulation on the caps that were leaking. It pissed me off, but wasn't affecting performance or starting hard, so I decided to let it be.

I remember there was someone from another site who was making brass return caps to replace the plastic ones. I wanted to buy a set at the time but they weren't really in production yet. I don't remember who it was or if they are still making them, but it could something to look into.

Do you still have the stock water filter on the driverside firewall? Those are known for being a air intrusion point if they don't seal after pulling the drain.

Archie

 

[argve]

Ataylor - he shouldn't have the separate filter/water catch system, with the 7.3's they have the all in one water separator / filter mounted to the engine bracket where our fuel filter goes. At least Ford did upgrade that to better system with the later designs.

Jim,
I'm with ya - the return line systems on these trucks leaves a lot to be desired. If you look at them wrong or say the slightest thing that might offend them they start leaking or sucking air. Check your fuel olive for wetness I have fought mine a couple of bouts this past summer along with the o-ring behind that fitting that goes into the injection pump. But typically over the years if I picked up some air it has been in the cap/o-ring combo on one of the injectors. So make sure you check those and the hoses associated with them very carefully like for example any rubber in the system. Rubber degrades with age so check it closely. I pity you it can be a pain to find.

I truly love the system that was on my Cummins - hard lined the entire way with banjo fittings - never any problems even when I cheated once and reused the copper on the banjo fittings - not the smartest move but thought I had some on hand and didn't so rolled the dice to get the truck back up and running.

Mel and I were talking about the return line system on the IDI and he said that since he opened up his diesel shop he found out that the IDI is the ONLY one that uses such a cheese-**** system to get the excess fuel back to the tank. What can you do... it is what it is...

I remember a few years ago seeing the brass caps you guys are talking about and haven't seen anything more about it other than a prototype set via the internet pictures. Thought to myself (at the time I owned my cummins) that when I got another IDI if they are available I was going to get me a set of those but sadly no more word on them.

 

[cpdenton]

I lay tile for a living. When you cut a tile and you are having to force it against something to make it fit the place it should go, it will always push back causing you problems on the next row of tile.

I think these return caps might be a similar thing. When I took my set of caps off, and made the new side of four caps that would drop down on to the injectors all at once, I thought to myself that these need to be perfect distance from each other. And side pressure from a piece of hose being too short or too long is going to put pressure on those o-rings. My caps have served me well so far without leaking.

Now, right after I did my return lines, my filter head started giving me all kinds of grief. I had to remove and plug the fuel heater opening, and I changed to the kind of fuel filter that does not use the bottom cover that was factory. It's all built together. Not much problem with air since then.

Good luck with it.

 

[icanfixall]

I feel we should set the plastic caps differently on the injecters. I think they should be turned so the line now loops from one to the other. That way there is no more problems with a too short or too long line between injecter caps. Its just a thought and you guys can run with it too.

 

[franklin2]

I thought I remember one of the older diesel rabbits having the same sort of system with small rubber lines running from injector to injector.

Correct me if I am wrong, but if we didn't have this type of system at the injector, we could not keep cranking on the engine till it started if it ran out of fuel. We would have to crack the injectors to bleed the air out or it would never start. That's one advantage isn't it?

 

[icanfixall]

When an engine cranks and fires up but then dies out. Thats a fuel leak down problem either at the injection pump or just before it. Both ends of the line that feeds fuel to the injection pump have an olive seal in the brass nuts. Its 5/16 in size. On the inlet side of the 7.3 filter head the line from the mechanical lift pump has a olive at the top of it but not the bottom. The bottom line connection is a flared fitting but the top is the olive in the brass nut. Its also a 3/8 olive. You can attempt to tighten these nuts but many times they are so hardened up they wont seal at all. Then its hell getting them out of the nuts but soaking over nite in brake fluid softens them.

 

[jas88]

Correct me if I am wrong, but if we didn't have this type of system at the injector, we could not keep cranking on the engine till it started if it ran out of fuel. We would have to crack the injectors to bleed the air out or it would never start. That's one advantage isn't it?

I believe you are right. Waaaaay back in the day I worked at an Olds dealership, the Olds diesel did not have return lines at the injectors as the IDI does, so if a customer ran the car out of fuel, they had to tow it in and we had to crack all the injector lines to get it to start.

 

[HammerDown]

When an engine cranks and fires up but then dies out. Thats a fuel leak down problem either at the injection pump or just before it. Both ends of the line that feeds fuel to the injection pump have an olive seal in the brass nuts. Its 5/16 in size. On the inlet side of the 7.3 filter head the line from the mechanical lift pump has a olive at the top of it but not the bottom. The bottom line connection is a flared fitting but the top is the olive in the brass nut. Its also a 3/8 olive. You can attempt to tighten these nuts but many times they are so hardened up they wont seal at all. Then its hell getting them out of the nuts but soaking over nite in brake fluid softens them.

That's an understatement...those little ******** can be mother fu*kers!

 

[icanfixall]

This was my experience removing those tough guys. I just kept picking at them with my dental picks I have. Took plenty of work but well worth the time and money. Those brass nuts do not have to be butt tight. Be sure you push the olive back on the tube a bit so the tube can fit into the female part of the brass fitting. All the nut does is compress'e the olive between the nut and the female fitting against the tube sealing it.

 

[jayro88]

My recommendation would be to go the e-pump route along with replacing the return lines. The e-pump makes it so the return lines being air tight isn't as important and it doesn't cost too much to do the conversion.......redoing the return lines is just making sure everything is in order. Mechanical pump has some positives, but the drawbacks can make for a headache.

And yeah....it's annoying to have these issues, but when your talking about a vehicle of this age you shouldn't buy it without expecting to have to redo stuff.

 

[redneckaggie]

I wanted to go an hose to replace all of the olive fittings, but damn that stuff is expensive. will probably wait until I start having problems to justify the cost of that, was going to cost me over $200 in fittings and line alone to go from my selector to fuel pump(6 inches) epump to plastic line(6 inches) and then an from the junction at mechanical pump block off up to the filter, then out of the filter to ip.

however I have had very good luck with the return lines, make damn sure to use proper length of hose and plenty of vaseline and I have only done them when I did injectors and one cap since in 8 years

 

[jim x 3]

When an engine cranks and fires up but then dies out. Thats a fuel leak down problem either at the injection pump or just before it. Both ends of the line that feeds fuel to the injection pump have an olive seal in the brass nuts.

... I have had very good luck with the return lines, make damn sure to use proper length of hose and plenty of vaseline and I have only done them when I did injectors and one cap since in 8 years

I'm still fighting this air intrusion issue.

I had previously replaced all of my return caps/lines with a kit from Russ Type4. I also replaced all of the olives except the one at the strange "T" fitting near #8. I have tightened the brass nuts on the olive fittings until they stop against the female side of the fitting. To get them tighter I tried adding a second olive, but then the nut won't thread on. So I cut a 5/16" olive in half radially and used 1 1/2 olives on each end of the filter-IP line. They got nice and tight. Things are better, but if I park overnight the truck will start right up in the morning then die. Then some considerable cranking is necessary to get it stumbling and starting.

The return caps and all lines are dry and clean. When I cracked the filter end of the filter-IP line, I can hear air entering the fitting. I am ready now to replace the filter-IP olive fittings with AN flare or compression fittings. It looks like the filter takes a 1/4" NPT male connection. Does anyone know what connection is required at the IP inlet?

Thanks and regards,