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Fuel Leak/Tank Question

5K views 26 replies 5 participants last post by  jackjtr 
#1 ·
Hey guys, I developed a fuel leak a little over a week ago. I originally thought it was from the bigger braided line which is on the input side of the fuel pump, but I took a look today and it turned out to be the braided return hose (I think).

If I'm going to replace that hose, I want to do all of them, as well as a new fuel filter.

Here's a picture of what I think is the return:



If the one on the right is the main supply with the finger screen, then the braided line on the bottom left hidden in shadow is the return, correct?

People who have replaced all of these hoses before, do you have the hose specifications, including the one coming off the pump?

Another question about the pump... is the metal unit connected to the braided hose the accumulator, or is it a check valve? Here's a pic:



Whatever it is, what are the three connections coming off of it? I noticed one of them is insulated.

Thanks so much in advance.


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#2 ·
That first pic is of the main fuel feed out of the tank which screws into the tank strainer which screws directly into the tank. The fuel return from the engine is right next to it. The other pic I'm not familiar with as you have a GenI car but I'm thinking the accumulator to the left and the filter to the right, maybe a couple more pics not so close-up or even someone else will chime in
 
#3 ·
I'm not 100% sure if that's the accumulator as there's a larger unit plumbed into the high pressure lines that looks like it's the accumulator. That might be a check valve so pressure doesn't flow back into the tank.

Anyone who's done this job on Gen 1 cars, do you know the hose sizes? Does the big line coming from the main fuel feed often crack? Mine looks to be in okay condition.


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#4 ·
The main feed from the tank only has gravity pressure on it but over the years the rubber does get old and stiff. If you are doing the rest of the lines back there I'd replace them ALL plus a new tank strainer, I'd also recommend replacing those under the hood as well leaking or not. The gas isn't going to flow back into the tank as the pump/filter assembly is under the tank. OH, one other thing, before you start tearing down I'd run out as much gas as possible and get a suitably sized hose clamp to pinch off the main line then finish draining into a gas jug, you don't want to take a gas bath. Have a fire extinguisher standing by just in case. I've done two of these cars, GenII, the 300SE has a single pump and the SEC has two, GenI's have a single pump IIRC but as your pics show the "plumbing" is slightly different but the manual will tell/show you everything as well as the part names
 
#5 ·
I believe M117 cars have two pumps while all others have one. I'll definitely be replacing all of the lines including the under hood ones. I'm thinking of the hoses as tires. Don't want to wait for cracked ones to blow.

I can't seem to find the section of the manual talking about fuel lines. I'm using the startek.info manual from 500Eboard.

I'll probably just jumper the pump and drain all of the fuel into a gas can. I think I read something on this forum about a guy getting fuel in his ear a couple of years ago. Yeah...no.


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#6 ·
Yeah, I forgot about jumpering the pump and letting it do all the hard work. It should go without saying BUT . . . . . be sure to get injection rated hose. One of these on mine is 5/8 sized (don't remember the metric size) and I used 315 PSI hydraulic hose, only needed about 2 or 3 inches of it and bought a foot
 
#11 ·
There are two types of rubber to metal line connections, one has the crimped sleeve and the other is some sort of compression with no clamp, mine had both. Both types have barbs and what I did was to carefully cut the sleeve up til I could break it loose and out of the groove, the other is simply (carefully) cut off the barb. I used rolled edge clamps made for fuel line and two years later nary a leak of any kind front or rear

1st pic shows both types of connections
2nd pic shows crimp fitting
3rd pic shows finished lines under the hood
 

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#8 ·
Be careful using hydraulic hoses or other hoses not specifically rated for gasoline. Fuels today can wreak havoc on hoses not intended for them, especially those fuels containing that scourge of society, demon alcohol.
 
#9 ·
Yeah, I definitely don't want to take any chances. The leak got really bad while the car was parked today. Have to get it towed tomorrow.

Can't find any local places with fuel lines rated for K Jet pressures, so I'll take to PelicanParts. Looks like they carry the crimped ones.

Can't I just clamp instead of spending all of that extra money on the crimped hoses? I understand that the crimped ones should be more secure, but I don't want to spend $25 on a fitting and a couple inches of hose if I can achieve the same for a fraction with a clamp.


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#14 ·
Sand down to smooth out old copper washers
Geez, and I thought I was cheap...

Actually, if you anneal the copper you can reuse them without any sanding or anything. If you sand them then there's a good chance the sides wont be parallel any more and they will leak anyhow, especially if you don't anneal them. Best to go with new ones.
 
#15 ·
I'll definitely go with new ones. They're listed for $0.25 each. Would rather have the peace of mind.

Does anyone know the diameter of the following hoses?

-Fuel pump > damper

-Damper > pressure reservoir

-Strainer > damper

-Return line > tank

-Underhood lines

I'm hearing mixed opinions about buying new crimped hoses versus clamping to the barbs within the crimped connections. Would rather not spend the extra cash for those hoses if I can avoid doing so and achieve the same seal. As long as I use high quality clamps and hoses, I *should* be good, right?

I mean a seal is a seal, as long as it's not leaking under pressure as far as I'm concerned...

I'm definitely doing a write-up with pictures for this job, including hose sizes which I can't find anywhere online.


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#16 · (Edited)
I don't know if GenI and GenII are different, thinking they are the same. I used 5/16 ID, 7.9mm injection hose under the hood from firewall to engine and back to firewall. The main feed from the tank I bought new from Autohauz online, I did that because it's a PITA getting it loose on the car as the strainer turns with it. While on that subject I found it's much easier to "set" the seat of the new fitting into the strainer on the bench, not much room up under and the hose has to end up pointing in a particular direction and much difficult to set it under the car. Once you do that take it back apart and install your new strainer (1 13/16 socket) then the new main feed being sure that when it's tight that it's pointing in the right direction. Others may have different ideas but this worked for the two that I did AND I subscribe to the "way to find the easiest way, give it to the laziest man on the crew" :wink :grin. The main feed to the engine from the pump assembly and the engine return to the tank were also 5/16, yours being setup different with one pump I wouldn't want to guess the size of the others. Hope this helps (I've got a bunch more pics too if ya need em)
 
#18 ·
How about the crimped return line? Did you buy a new one or "hack the crimp"?

Some more pictures would be awesome if it's not too much trouble.
"hack the crimp" LOL I didn't like the idea of removing to replace the metal lines (and is what you'd have to do if you don't "engineer" the replacing of just the rubber) All three lines under the hood (I have a fuel cooler, no, it cools the fuel before returning it to the tank), both the feed from the pumps to the engine and the return line to the tank, the vent valve line on drivers side of tank (can't remember it's size), on my SEC there was a hard line with rubber between the two pumps, that rubber was replaced, the only line with fitting I bought was the main feed from the tank (I DID buy a new return to tank line out back for the SE, that was before I was told how to swap just the rubber)

Here are some more requested pics, the ones on the pump assembly were from the 300SE and under hood was the SEC, not a problem glad to share em

1 and 2, bottom of tank
3, vent valve
4, firewall
5, to and from engine
 

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#20 ·
Yeah, don't want a Car-B-Que :eek This is what my fuel lines to and from the engine looked like the day I bought her and discovered the feed line from the pumps to the engine was actually leaking :eek :eek Needless to say she remained parked until the "BOOM" factor was fissed (repaired :wink)

I doubt you'll have this but the big brass / copper thingy is the fuel cooler, not all cars have them and they weren't until later
 

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#21 ·
Yeah, I believe all gasser 126s have it. Mine still has the factory insulation on it.

I've got a bigger issue on my hands now. Apparently police can't read notes on cars. Now I have a bent drivers door from an idiot tow guy breaking into my car and a huge bill because some cops shouldn't be cops.


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#22 · (Edited)
That may be from the property owner where your car was stranded didn't want it there, notes don't usually work. I had to leave the SE overnight at a Tupelo truckstop and I went in and personally talked to the manager explaining what was going on. The car was parked in the lot out of the way. He said he'd pass along the word to the other shifts, no problem with it being left there

And that sucks what the tow guy did to gain access to your car, I'd inquire to Perry Mason as to their liability for damages
 
#23 ·
Unfortunately, this was a public parking area near a park in a very affluent part of town (I'm working for HGTV at the moment and we're shooting a house across the street). I decided the fuel leak had gotten to the point where I didn't feel comfortable driving. Left the note, and didn't expect anything to happen.

Now I'm stuck with a bent door frame, storage fees, tow fees, and I still have to order my new hoses.

I wish they'd focus on busting the crack dens in the rough parts of that town instead of picking on a hardworking kid with car troubles... Cops will be cops I guess...

No work tomorrow. I could use a drink.


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