Problem with air in the fuel lines

[albert rodrigues]

I thought I had my problems licked with the fuel system but unfortunately do not and need help and suggestions. This is what I have done on the fuel system thus far.

I have replaced all my flexible fuel lines and hose clamps
I found a band clamp which covered a small hole on the hard line running along the frame back towards the fuel tank. I used a brake line from a local parts store and bent it to shape and reinstalled

After the hoses were replaced, I was able to get it started for a few minutes and did not have any leaks on any of the new hoses and connections.

The engine still cut off and I went to the next step. Using a suggestion from a previous post, I pressurized the tank with a few pounds of air, I could not find any leaks. I used a spray bottle with soapy water and applied it generously to all the connections.

After all these attempts the symptoms remained the same. The air is mostly accumulating at the fuel filter and only after removing it all at this location can the engine be started. The bleed screw on the side of the pump remained mostly air free.

I have not been able to find a replacement air filter to test if the gasket is the source of the problem. My soapy water test did not show signs of the filter being the problem but I am not ruling it out. BTW, napa gold filter 3393 does not fit my B engine, it is too wide and tall and interferes with the radiator hose just below it. I ordered a FRAM filter P4178 and hope it will do the job, I need something no wider than 3" and 3" high.

Could anyone tell me what the symptoms of a leaky primer pump would be? Where would the air accumulate? I am thinking of getting a bosch replacement in lieu of the recent posts and relatively inexpensive part.

How about the injectors? Can those leak if not properly sealed?

Can the fuel cap cause a problem if not sealed properly? Would this type of leak be obvious? I do not have may 'wet ' areas on the fuel lines.

I have removed all the hard fuel lines after not having any luck and will test all the lines one by one. Can anyone suggest a supplier for the hard lines should I find a problem? Does anyone carry a complete kit?


thanks in advance for all the help.

[roscoFJ73]

Originally Posted by albert rodrigues

I thought I had my problems licked with the fuel system but unfortunately do not and need help and suggestions. This is what I have done on the fuel system thus far.

I have replaced all my flexible fuel lines and hose clamps
I found a band clamp which covered a small hole on the hard line running along the frame back towards the fuel tank. I used a brake line from a local parts store and bent it to shape and reinstalled

After the hoses were replaced, I was able to get it started for a few minutes and did not have any leaks on any of the new hoses and connections.

The engine still cut off and I went to the next step. Using a suggestion from a previous post, I pressurized the tank with a few pounds of air, I could not find any leaks. I used a spray bottle with soapy water and applied it generously to all the connections.

After all these attempts the symptoms remained the same. The air is mostly accumulating at the fuel filter and only after removing it all at this location can the engine be started. The bleed screw on the side of the pump remained mostly air free.

I have not been able to find a replacement air filter to test if the gasket is the source of the problem. My soapy water test did not show signs of the filter being the problem but I am not ruling it out. BTW, napa gold filter 3393 does not fit my B engine, it is too wide and tall and interferes with the radiator hose just below it. I ordered a FRAM filter P4178 and hope it will do the job, I need something no wider than 3" and 3" high.

Could anyone tell me what the symptoms of a leaky primer pump would be? Where would the air accumulate? I am thinking of getting a bosch replacement in lieu of the recent posts and relatively inexpensive part.

How about the injectors? Can those leak if not properly sealed?

Can the fuel cap cause a problem if not sealed properly? Would this type of leak be obvious? I do not have may 'wet ' areas on the fuel lines.

I have removed all the hard fuel lines after not having any luck and will test all the lines one by one. Can anyone suggest a supplier for the hard lines should I find a problem? Does anyone carry a complete kit?


thanks in advance for all the help.

A few ,actually a lot of owners have had problems with the primer pump leaking.
They dont cost much and it would eliminate one item of doubt.

I think the injectors can leak air if not tightened properly ,but with the pressure involved,I would expect fuel seepage also.

Im dealing with my own air leak in my 75 series and Im pretty sure its around the hoses where they join the fliter head

[albert rodrigues]

RoscoFJ73, The primer plunger I have is labeld MADE IN GERMANY and screws in when not in use. I thought I read on the forum that the original pumps were from Germany. As you said, if it is original, maybe it's time to get a new one in there. Removing it will be the next post, how do I get a wrench/spanner in below the primer?

[roscoFJ73]

Originally Posted by albert rodrigues

RoscoFJ73, The primer plunger I have is labeld MADE IN GERMANY and screws in when not in use. I thought I read on the forum that the original pumps were from Germany. As you said, if it is original, maybe it's time to get a new one in there. Removing it will be the next post, how do I get a wrench/spanner in below the primer?

The original pump would have been a japanese Denso unit but they are a copy of a Bosch design.
I haven't removed that type but Im sure someone else here will have dealt with it before

[lostmarbles]

My 2c worth:

• German engineering is generally very good so I wouldn't replace your primer pump unless you have first confirmed that it is leaking diesel.
• People have used "crows foot spanners" to remove them before (according to previous posts) so you could probably do a search on "crows foot" to find those threads. These spanners are specially designed to get into tight spaces. But then again, if the pump is knackered - just grab hold of it with vicegrips because damaging it is not a problem.
• When I pressurised my tank with air, I stuffed tissues (facial tissues) around "suspect areas" and then checked whether they became damp with diesel.
• I don't see how you could use the "soap and water method checking for air leaks" unless you had first drained all your fuel system of diesel - Which would be a pita to do!

Cheers
Tom

[albert rodrigues]

Good point lostmarbles on the soap and water. I was desperate at that point and clearly not thinking.

When I pressurized the tank, I had a pretty clean engine compartment and someone there to look at the lines but did not think of using dry rags. Throughout the process I also noticed a very slight sound of what appeared to be air entering the fuel lines. I could never ID where the sound came from but it appeared loudest near the primer pump area. It was very hard to hear, however. Do you have a guess as to why the air would end up at the fuel filter bleed plug, or is it hard to tell because it is the high side of the fuel system?

How do I confirm the primer does not seal properly? It may be too late to test everything properly since all the fuel lines have been removed and will be tested individually. I did follow your post on the primer pump and went ahead and ordered a bosch pump from autohaus. It will be a backup if I can prove the existing pump is ok.

I'd also like to get a few replacement fuel injection lines. The bj I have came from central america and I have a few lines that were welded in spots. Judging the quality of the work done, I'd like to eliminate some of the lines and potential future problems.

[lostmarbles]

Originally Posted by albert rodrigues

....did not think of using dry rags....

In my opinion, paper tissues would work better than rags because they use less diesel to become wet and soggy.

...Do you have a guess as to why the air would end up at the fuel filter bleed plug, or is it hard to tell because it is the high side of the fuel system?......

Any air entering the fuel at any point from there right back to your fuel tank will all end up there at the top of the fuel filter. (And that includes any air that enters the little bleed line that runs from the injectors back to the fuel pump inlet - which is a common leak source - particularly where that little bit of flexible hose is near the cylinder head.)

...How do I confirm the primer does not seal properly? ...

My faulty ones (and all the faulty ones that I have read about) drip diesel fuel when they are operated/pumped.

... and I have a few lines that were welded in spots. Judging the quality of the work done, I'd like to eliminate some of the lines and potential future problems.

That sounds very sensible.

Cheers

[lostmarbles]

How are you getting on?

Here's a drawing of the fuel circuit from the manual:



I've coloured (in red) the "suction side" of the circuit where you should be looking for leaks.

That little bit of flexible hose I've pointed to is very prone to leaking because it gets a lot of heat from the cylinder head and often the hose clips don't fit the small tube size very well (and are therefore difficult to stop leaking). And being so high up - You NEVER get diesel leaking out there (unless you pressurise the fuel tank).

[albert rodrigues]

Thanks Tom for the diagram. In retrospect I went to the last step too quickly without carefully looking at everything. I now have all the hard lines off and someone is testing them for me. Before the hard lines came off I replaced the small flexible hose on the return. As you have experienced, I could not use the proper hose clamps and had to use zip ties. The were closed tight but may have leaked because they were up high. I never second guessed the new line and zip ties but now wonder if that was the problem.I also replaced the hard line to the tank. This was the line I thought was causing my problem since I found a 3mm hole in it with a small clamp over it. This line was replaced with a hand bent brake line of same diameter and with proper clamps.The primer pump does not leak when pumped but has a bit more side to side motion I would guess, this is my first LC so I don't know for sure.I am currently pricing replacement hard lines. I found used ones but the price seemed much to high. Tomorrow I will pickup the new fuel filter, hopefully the Fram is the correct size unlike the Napa gold filter. The filter should rule out some more trouble spots. I'm also going to check with mcmastercar.com to see if the have the proper clamps. They are a web based hardware store with almost any type of hardware you can imagine. Thanks very much for you input, I'm sure I will need your experince again as soon as I have the parts and time this weekend.

[albert rodrigues]

the web site for mcmaster-carr is McMaster-Carr
sorry for the eroneous post.

[lostmarbles]

Originally Posted by albert rodrigues

.... As you have experienced, I could not use the proper hose clamps and had to use zip ties.......

I'm not keen on the "zip tie" method because the plastic in them is likely to stretch (especially when subjected to heat). I used the smallest size stainless hose clips I could find. (I did have better-fitting clamps on hand but they weren't stainless.)

.....The primer pump does not leak when pumped but has a bit more side to side motion I would guess, this is my first LC so I don't know for sure.........

If it doesn't ever drip diesel - Then my opinion (based on my experience up to this point in time) is that it is likely to be OK.

....I am currently pricing replacement hard lines. I found used ones but the price seemed much to high. ........

I don't like your chances of getting new ones unless you can find a specialist diesel shop who have experience in making them up. (The high pressure lines are very thick-wall.)

...Tomorrow I will pickup the new fuel filter, hopefully the Fram is the correct size unlike the Napa gold filter.....

The Fram part number that fits mine is P4178

[albert rodrigues]

I was just browsing mcmaster.com and found some one-use band clamps similar to ones I just removed on my wife's fuel filter on her bmw. I like that they are stainless and come in very small sizes. If I decide to buy I will let you know what I think...The installation tool is the most expensive part but I can use it on other projects in the future.
I spoke with someone at EBIcruiser parts and was told they could get new lines. I'm waiting for a reply for costs and availability.
I think I will hold off on installing the primer pump, at this point I do not want to add any more potential problems until I can get it started for more than a few minutes.
I ordered that fram filter, I think I found that number in one of your previous posts. BTW, I am putting a spread sheet together for part numbers and will attach it to this thread. It is just getting started but I would like to have a few people like yourself comment on the layout and content and columns that should be added. I think that having a refernce list in one file would help everyone on MUD. When I finalize the layout I will be happy to try to put all the part numbers in the file and share with everyone again.

[lostmarbles]

Those clamps sure look good and so does the spreadsheet Albert.

And soon we'll have more info for our B engines on MUD than there is for the 3B!

[albert rodrigues]

Can anyone inform if the injector pump bleed screw should have a rubber washer or O ring?

[lostmarbles]

Originally Posted by albert rodrigues

Can anyone inform if the injector pump bleed screw should have a rubber washer or O ring?

I was hoping someone else would reply to this.

All I can say is that I have never seen any sign of any O-ring on either the bleed screw on my fuel filter or the one on my injector pump body. So I would assume they are designed similar to the bleed nipples on brake cylinders - which I'm pretty sure don't have any O-rings for sealing.

Why do you ask? Is yours permanently leaking?

[albert rodrigues]

On the pump body I do not have an O ring, on the filter bleed screw there is a small rubber washer, I'm not sure if it is original however. Do you know where I can get replacement screws for both positions?

Well, I spent the weekend putting all the old fuel lines back on the BJ because I did not find any problems with pin holes, etc, even where there are welds. After getting it all together late last night I still had a tremendous amount of air in the system, so much so, I could not get any fuel pumping. I returned to the forum afterwards just to check if anyone else had any similar experiences. Nothing was an exact match but I was inspired by a thread regarding the water separator leaking.

This morning, I found that one of the lines (return line from the leakage pipe at the pump body) installed yesterday was not properly torqued down and that I will definitly need a source for the metal/rubber washers used on all the fuel lines as they are all quite worn out. After trying to get her started I still could not get the lines bled. I decided to try to bypass the water separator and a few pumps later I was able to get the BJ started and running well all day I would like to make sure I use the separator becuase during the trouble shooting process, I found a large amount of dirt in the bottom of the body, about half full with soil. Attached is a picture of the separator, it was made in England and has a Kralinator filter on the top part. The bottom has a rubber seal that is a bit worn, the top seal is accomplished by the filter and I am not sure if a new filter comes with an upper gasket or seal. Lastly, the separator has 4 inputs, the way the truck was setup was that the line from the tank went into port 1 which has an arrow pointing out towards the tank? The port labeld 2 has an arrow pointing in towards the separator and was rounted to the pump body? The filter on the separator is a Kralinator F961A. Can anyone let me know if this was a standard item on my BJ and if I should re-route the lines following the arrows? Where can I get that filter as well?

[roscoFJ73]

Hi Albert. That looks like a generic type filter head to me that takes a very common type filter and they are well proven.
I see them on ebay and my parts store sells them for $59

You do get a new gasket when you buy the filter(well I did and mine is same type)
If I am correct ,yours is the Racor/Delphi 296 type filter.
Most of them have a glass bowl so you can see the crud or water,but yours has a metal container

The best bit about those filters is you can get quality replacements for peanuts,$6-7
I fit them on the bench to makes sure I get the o rings right.

I think there are one way valves in the couplings that can allow fuel to flow backwards when they are worn out. You can probably buy replacement parts at a good diesel shop.
The filters are good for about 50 litres an hour