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Fuel line routing at rear of engine

topeju

topeju

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Hi all,

Where exactly should the fuel lines be attached at the rear of the engine?

My 1996 Suburban 2500K 6.5TD bent a connecting rod last year, and now that I finally got it running again, I noticed a fuel leak. In the process of debugging the fuel leak, I removed the intake and all the fuel hoses on the top of the engine (around the valley). I also pulled down the fuel lines behind the engine in the process as some of the upper hoses were rather old, and of course the clamps on them were facing the firewall. I found the leak in the FFM (silly me, I'd installed the water in fuel sensor upside down, preventing a good seal), but now have to put everything back together.

There is the obvious V-shaped bracket that attaches to the engine-to-bellhousing bolts, but when I pulled the lines down, a small bracket (will try to get a picture tomorrow if necessary, but it's just a U-shaped metal strip with holes in both ends and some rubber lining) also fell down from somewhere, probably further up, and I have no idea where it should be attached to.

There is one bolt on the rear of the block, but I think it is slightly too far to the left for the bracket to be attached there (also, that bolt does have a plain aluminum bracket on it, don't know what for). The bolt holes on the top of the wall on the rear of the engine are also too far. The only place I could think of that might be possible is the topmost engine-to-bellhousing bolt, but that already has one end of the V-shaped bracket so it's probably a bit close to the other attachment point.
 
The return line runs essentially the same, except of course doesn't connect to the FFM but the thin metal line that comes from the front of the engine. The question really is where are the lines attached to? One obvious point is the V-shaped bracket, but there probably is another point too, somewhere.
 
10EA91DF-FD34-41C0-9519-59C3D2A0062B.jpeg
This is what the small bracket looks like. Where should it go to?

Edit: The more I think about it, the more I'm convinced it should be on the top engine-to-bellhousing bolt, as it is the only one that can reasonably be reached, and it would have been deattached when I removed the engine (and, now, when I pulled the fuel lines down and out).
 
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YUP, top bell housing bolt, IIRC, I also think that maybe that bolt might have had a stud/nut affair on the head end of it to attach the hoses clamps to.
I could be wrong and I cant crawl underneath the truck to look at it for, probably another month. LOL
 
Yes, I got proper fuel hoses to replace the 24-year-old ones. And indeed that top bell housing bolt had a stud to which I attached both brackets (the smaller one pictured above and one end of the the V-shaped one). Putting them in place was a major pain in the a$$ (or, more accurately, legs and lower back), as I had to play Spider-Man to reach the stud, and there is precious little space between the firewall and the bellhousing to tighten the nut.

But the engine now runs nicely, with no stuttering like we had earlier. Still got a little bit of fuel on the garage floor, but that is probably from the bleeder valve on the FFM - I opened it a touch too far and it leaked some fuel when we were bleeding the system. (Or some of it could be left over from the earlier leak for all I know.)

I guess I'll have to post in the 6.5 carnage thread about the original problem last year -- it's taken me 11 months to fix the engine (with help from a friend who actually knows a thing or two).
 
Dammit, the fuel leak came back when I went to the DMV. I have yet to try to see where it is, exactly, but there are drops coming down every second or two, in same place as before (between the starter and the bellhousing), implying the problem is still somewhere in the valley. Sadly, I don't have time this week to investigate the issue.

In order to fix it, I think I'll have to create some sort of platform where I can just lie down above the engine bay, as using the storage bin and the top of the radiator to kneel on was rather painful.
 
Top side creeper. Then after seeing the price, you’ll figure how to diy one.

Sounds like ffm leak usually the stupid sensor. Really a good sensor to have, just wanna call it names by time your done.

Good time to add the fuel pressure gauge to the ip inlet side and do FTB mod if ya have to order parts
 
Yeah, just checked the prices, and I think I'll MacGyver something using a plank, some scaffolding I have (that is too narrow to fit over the car), and the electric winch in my garage ceiling.

And yes, it might well be the FFM again. Though before we put it back in place, we changed the O-ring on the sensor and pressure tested the FFM with 15 psi and there were no leaks.
 
The only thing worse that trying to lay out over/crawl around on a Burb engine compartment for hardness on one's legs and lower back (I have a '98 Burb 6.5), is trying to lean over knee to mid thigh height edge of a Camry engine compartment and work on something (I've owned and worked on multiple '95-'05 Camrys).
 
Idk, when I got my arm trapped in the stupid 300d Mercedes and started asking for guys to cut the front of the car apart with a torch...

@topeju if you run a jumper wire to power up the lift pump non stop, may help find it. If you don’t have the ops feeding a relay tothe lift pump yet... Do it but add a switch to turn it on under the hood for servicing the ffm. They come pre made- ut that is all after you get these issues fixed.
 
Pretty sure it was still the filter: after driving the truck back into the garage, I noticed the bracket that is holding the wire harnesses (attached with the same bolts as the FFM) was damp with diesel, and the truck hadn't been run for a week. I changed the filter itself, and I'm pretty sure the leak stopped.

Not quite 100 % sure on that leak being stopped, but had the truck running for 15-20 minutes and didn't get anything on the floor. However, when I backed it out again and stopped on a slight incline, I saw some drops of diesel falling from the same old place. I am fairly optimistic these are just the diesel draining off the valley after some was spilled when I changed the filter, but will have to check again when I get new parking brake cables and brake shoes next week (those were another reason the truck failed its inspection).

I don't see anything wrong on the old filter, and as I mentioned earlier, we pressure tested it with 15 psi. It was the filter that was on when I bought the truck last year, but the Wix filter I got as a replacement seemed like a complete dud (e.g. the hose port on the bleeding valve was not connected internally as far as I could tell) so we switched back to the original one earlier. What I put in now is a new ACDelco one.
 
Check the injector return hoses. I had to replace one of mine today because it started leaking and dripping down on the ground behind my front tire. It’s the little hose on each injector that connects to the next injector.
 
And especially check the end cap on the rear most injector. They do sometimes develop a hairline crack internally over time, that is even with the top of the nipple, and that crack can migrate through and leak externally. Seen this with the old-style clamp-on type injector return lines.
 
I checked the return hoses earlier and they had no leaks. Also, the diesel was dripping down between the starter and the bellhousing, which to me would indicate it was coming down from the valley on top of the engine block.
 
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