240 fuel leaks

i need help. Installed new sending unit and larger in-tank pre-pump on 1981 242 turbo. Fires up but fuel leaks. Inline pump and hoses not leaking. Appears to be running down hoses from in-tank connections. All hose clamps on in-tanks pump are secure. But fuel is accumulating on top of bung unit. Also, turbo trouble light on dash is lit. Any advice would be appreciated.

Did you properly attach the original fuel line to the sending unit or did you accidentally attach the shielding. I ran a new hose between the main pump and sending unit when I replaced all of that

Sounds like in-tank pump outlet connection on top of bung is leaking. Or possibly the fuel return line.

Your era of turbo I believe has in tank pump to main fuel pump to accumulator to fuel filter to distributor. Depending on the accumulator type, if it has a leak it'll return to tank via that third tube.

If the fuel is accumulating on top of the bung, it's either:
1. Pushing out around o-ring (unlikely as you'd have fuel pouring out of filler neck too since sender is highest point on tank
2. leaking from one of the 3 top ports.

Since #2 is only possibility, then you have the following possible leak points
1. Sender line to main pump - this is just rubber/fabric hose clamped on over a flared metal head. When removing the hose to put on the new sender did you cut the hose in any way? I assume sender not scored because it's new (unless refurbished?)
2. Return from distributor and such - On my B21FT it's a rubber outer on a shrink fit nylon inner - does not disconnect from the sender. I assume with a new sender you likely have a clamp for it rather than heat shrink original style. Is the clamp a proper fuel hose clamp or just a band clamp that cuts into the fuel line?
3. Return from accumulator - if you have this third line, flow in it from the accumulator means your accumulator is leaking, so that could be causing some low pressure (which may be able to set turbo trouble light?). Otherwise you should just have a cap.

Can you see if any of the hoses have fuel drip markings on their underside (or even feel for it?). That could tell you which hose.
If no drip feelings, I wonder if the sender or return where it's brazed to the cap is broken slightly / cut into the line itself and is allowing leaks. you could bypass the fuel relay and force run the pumps and watch for accumulation on top of the bung nut.

Hi all, thanks for the response.

I triple-checked hose connections on top of bung. Pretty straightforward, as hose sizes and metal lines are all different sizes.
Bench tested pre-pump before install and it worked fine. I did cut a half inch off one hose so I could twist the small bit of remaining hose off the metal line. That was the one that on the original unit had a plastic shield. The replacement sending unit did not have a plastic shield.

Started it up this morning and top of bung is dry, so leaks are lower down. Fuel still running down from at or near main pump.

During uninstall of old sending unit and pre-pump I tugged on existing return line pretty hard to pull up enough line for slack, so I'll be checking all lines in and out of main pump when I receive a replacement main pump next week. The small section of hose from the top of the in-tank pre-pump had disintegrated except where the ends connected to the pump and metal line. So I'm sure I have a lot of debris in the accumulator/filter near the main pump. I am looking for a replacement for the accumulator/filter. Is that a generic product, or do I need to find one specific to this car?

I also have a new Mehle fuel filter that goes on the firewall, so I'll install that as well.

I also just replaced the stock boost gauge with a vdo so I can get a precise measure of boost. Of course, now the turbo caution light on the dash is on. So I think the is a possibility:

"Return from accumulator - if you have this third line, flow in it from the accumulator means your accumulator is leaking, so that could be causing some low pressure (which may be able to set turbo trouble light?). Otherwise you should just have a cap."

Wish me luck, I'm going in!

Someone will correct me if I?m wrong but I believe the fuel accumulator on turbo cars does not have a vent

Radtap said:

Someone will correct me if I?m wrong but I believe the fuel accumulator on turbo cars does not have a vent

Click to expand...

it's a vent to atmosphere (there's a screw on the back and a little slot space on either side of it. If the diaphragm fails fuel will spit out this hole area)

But with cheaper accumulators sometimes being vented and variation year to year of all sorts of stuff, easier to state all possibilities than miss out.

Hi again,

Can anyone who's replaced the tank to main pump fuel line tell me if it was easier threading it through the hole from the top (trunK) or from the bottom? I'm replacing the main pump, accumulator/filter located near the main pump, and the filter on the firewall. I figure I'm going to dislodge some debris in the process, so I may as well replace the whole line while I'm at it. I found an OEM at Boston Volvo and found a Bosch accumulator/filter at FCP Euro.

erichobart said:

Hi again,

Can anyone who's replaced the tank to main pump fuel line tell me if it was easier threading it through the hole from the top (trunK) or from the bottom? I'm replacing the main pump, accumulator/filter located near the main pump, and the filter on the firewall. I figure I'm going to dislodge some debris in the process, so I may as well replace the whole line while I'm at it. I found an OEM at Boston Volvo and found a Bosch accumulator/filter at FCP Euro.

Click to expand...

On my sending unit I was disconnecting the return line on the underbody of the car and pushing the return line hose back down - it's not amazingly convenient (I had to put the sender in in one orientation, rotate it so the return line could be coiled in, then rotate to push the return line back down through the hole to underbody.

For the main fuel line, I struggled to get the right size fuel line clamp on (not sure if my rubber hose had swelled over the decades) while the sender unit was in place. At the same time, I'm not sure it would be easy to snake two hoses down in the body-fuel tank space. Do a pre-test of the clamp to make sure it goes on easily (ideally on the hose before sliding onto sender so then you just need to tighten).

I'd then suggest threading it through from the underside and once sender is in place, pull it onto the appropriate port. Not a lot of space to get the sender and return line in as is.

As for accumulator, there's a few types that'll work and be cheaper than a direct replacement: http://turbobricks.com/forums/showthread.php?p=6253722#post6253722

I had an easier time running the line through from the trunk, I thought I was having issues with my fuel accumulator and removed it, ran a line direct to pump then to the hardline and had no change, never put it back in.

Hey,
So the leak is where I pulled the rubber line off the barbed plastic coated nipple on the metal line that feeds the main pump. So there's that. New fuel line on the way. Also clamps, so many clamps.

erichobart said:

Hey,
So the leak is where I pulled the rubber line off the barbed plastic coated nipple on the metal line that feeds the main pump. So there's that. New fuel line on the way. Also clamps, so many clamps.

Click to expand...

IIRC the sender to main fuel pump should have a rubber hose that comes completely off the connection point on the sender. It sounds like you pulled off an exterior later and left a stiffer interior behind.

The return line up until a certain vintage was a heat shrunk nylon fitting with a rubber surround that really doesn't come off the sender.

Either way, good to have the spot identified and as long as you have fuel line style clamps you likely won't have a future leak problem.

Actually I was wrong. The line that was loose came off the sender and went to one of the metal fuel lines that run to the engine. Long heat-shrunk nylon fitting on the metal line, shorter one on the sender unit. Replaced old rubber surround with new. Cinched both ends down with fuel injector clamps. Nylon fitting on sender is gone. Replacement is bare metal. No more leaks.

Tomorrow fuel filter on the firewall gets replaced. Tuesday new Bosch main fuel pump and accumulator/filter that sits next to main pump. Next weekend new downstream oxy sensor.

She still runs rough, so after fuel lines going into pcv. Replace all vacuum lines and fortify with clamps.

After that, don't know. Compression tests and down pressure tests maybe. Turbo is spooling up, no noise, VDO gauge shows movement. Not sure how to proceed, so going through system by system.

No.1 plug shows oil. Chased and reseated. No real change.

erichobart said:

Actually I was wrong. The line that was loose came off the sender and went to one of the metal fuel lines that run to the engine. Long heat-shrunk nylon fitting on the metal line, shorter one on the sender unit. Replaced old rubber surround with new. Cinched both ends down with fuel injector clamps. Nylon fitting on sender is gone. Replacement is bare metal. No more leaks.

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That's the return of excess flow to the tank so semantically it's a metal fuel line that runs from the engine.

I'm having trouble locating the original accumulator for an 81 b21ft, the one with a nipple on the back and a line back to the sending unit. Do you think it would be ok to use the later version that just has a release port on the back? Also, is there only a downstream o2 sensor on this model, or a second upstream sensor as well? Bentley's starts at 83, so not always helpful with mine.

nvm, found hairy baboon's thread on the trials and tribulations trying to find a replacement with no third line, gonna try the 034

You?re going to want to get the specific Volvo greenbooks for your year and the sections you need. K jet is a whole **** show in of itself. That Bentley book would be about 3 times thicker. There is only one o2 and it?s a single wire style, it can be found in a couple different spots. I imagine it wouldn?t make much of a difference between the turbo and NA accumulator as the only different is one is intended to vent to the tank and the other vents to atmosphere. The one with the nipple just vents to the tank then out the gas cap or up to the black box so you?d just be cutting out the middle man. My car runs and drives without an accumulator. Look on eBay for 1981 Volvo greenbooks. I have the kjet and electrical book for 80 which I imagine is pretty close to the same thing, there?s likely differences though

An 81 B21FT car has a lot of first year only parts. Like the lambda computer. The idle air control motor and computer, too. I would also be sure to get the wiring diagram green book. The print ones are so nice to use.

Most of the newer parts can be used with little or no modification. But you do want to be careful that you got the right part to do so.

dl242gt said:

An 81 B21FT car has a lot of first year only parts. Like the lambda computer. The idle air control coolant temp sensor and computer, too. I would also be sure to get the wiring diagram green book. The print ones are so nice to use.

Most of the newer parts can be used with little or no modification. But you do want to be careful that you got the right part to do so.

Click to expand...

^Fixed. Idle Air Valve is same through most of 1983. Late 1983 received B23F style small air valve.

almost done with all fuel line components except hard lines. new primary pump goes in tomorrow. later model accumulator on the way, that eliminates line. replaced filter on bulk head. not much left in fuel line so still looking for low idle problems. also dies at idle at 200. cleaning air box and intakes, girl has been dozing. mixture is fuel rich, carbon deposits on tail pipe. ok up to 2k but the dives to stall.