Cleaning the Fuel System

[Justin51982]

So I just finished reading this great write up.....

http://dmctalk.org/showthread.php?637-How-to-clean-out-fuel-tank-and-flush-fuel-system-BEFORE-you-try-to-start-the-car

I had one thought though in regards to cleaning the fuel lines from the tank back to the fuel distributor....Instead of running the B12 through all the lines, wouldn't it be just as effective, but cleaning and easier to use my air compressor and a tapered nozzle and blow the system out that way?

Has anyone done that? If so had success? I'm just curious because I am planning on tackling a good portion of my fuel system this weekend.

[OverlandMan]

So I just finished reading this great write up.....

http://dmctalk.org/showthread.php?637-How-to-clean-out-fuel-tank-and-flush-fuel-system-BEFORE-you-try-to-start-the-car

I had one thought though in regards to cleaning the fuel lines from the tank back to the fuel distributor....Instead of running the B12 through all the lines, wouldn't it be just as effective, but cleaning and easier to use my air compressor and a tapered nozzle and blow the system out that way?

Has anyone done that? If so had success? I'm just curious because I am planning on tackling a good portion of my fuel system this weekend.

My 2 thoughts here would be moisture and amount of pressure (assuming 90 psi).

Are your lines original? If so, I'd highly recommend replacing ALL of them sans the metal lines. This is coming from someone who's car had a 20 second fire due to a pinhole in a fuel line.

[David T]

My 2 thoughts here would be moisture and amount of pressure (assuming 90 psi).

Are your lines original? If so, I'd highly recommend replacing ALL of them sans the metal lines. This is coming from someone who's car had a 20 second fire due to a pinhole in a fuel line.

The logic in using a solvent and flushing it through the lines is that it hopefully would break down any sludge and wash it out. Air won't do that, it will only blow it out if it is already loose. The amount of moisture in the compressed air is negligible and even at 90 psi you won't hurt anything. A lot of this is a judgement call. How intensive you get is a function of how badly the fuel system is fouled up. One good way to judge is the amount junk at the bottom of the fuel tank.

[Justin51982]

The logic in using a solvent and flushing it through the lines is that it hopefully would break down any sludge and wash it out. Air won't do that, it will only blow it out if it is already loose. The amount of moisture in the compressed air is negligible and even at 90 psi you won't hurt anything. A lot of this is a judgement call. How intensive you get is a function of how badly the fuel system is fouled up. One good way to judge is the amount junk at the bottom of the fuel tank.

I know that at least portions of the fuel system, lines and whatnot were replaced when Hervey owned the car, It also looks like he updated the fuel pump and baffle in 2004 (according to the date on the part) and I know the last time it was ran was 2000-2001.

The tank was pretty empty, there is a little bid of sediment at the bottom, but the take was pretty much empty when I pulled the fuel pump and you can see more silver than black at the bottom of the tank.

I also now have new fuel stainless distributor lines, maybe I'll start out by cleaning the tank it self with B12 and then disconnect the fuel distributor and push air through the system. Depending on what comes out from that, I should be able to better determine if I need to get more invasive.

[David T]

I know that at least portions of the fuel system, lines and whatnot were replaced when Hervey owned the car, It also looks like he updated the fuel pump and baffle in 2004 (according to the date on the part) and I know the last time it was ran was 2000-2001.

The tank was pretty empty, there is a little bid of sediment at the bottom, but the take was pretty much empty when I pulled the fuel pump and you can see more silver than black at the bottom of the tank.

I also now have new fuel stainless distributor lines, maybe I'll start out by cleaning the tank it self with B12 and then disconnect the fuel distributor and push air through the system. Depending on what comes out from that, I should be able to better determine if I need to get more invasive.

Actually Acetone works very well to clean the tank. Then you can put some B12 in the tank and run the pump. That will circulate the B12 from the tank, past the accumulator, through the fuel filter and to the mixture unit where the pressure valve will dump it back to the tank. Once you have that circuit clean remove the fuel injectors and push down on the air sensor plate to get the B12 to come out of the lines going to the injectors. When you have B12 coming out clean, install the fuel injectors and see what the patterns look like with fuel. Once you have them all spraying replace the fuel filter and if necessary, the accumulator. Replace any deteriorated parts in the tank.

[Justin51982]

Actually Acetone works very well to clean the tank. Then you can put some B12 in the tank and run the pump. That will circulate the B12 from the tank, past the accumulator, through the fuel filter and to the mixture unit where the pressure valve will dump it back to the tank. Once you have that circuit clean remove the fuel injectors and push down on the air sensor plate to get the B12 to come out of the lines going to the injectors. When you have B12 coming out clean, install the fuel injectors and see what the patterns look like with fuel. Once you have them all spraying replace the fuel filter and if necessary, the accumulator. Replace any deteriorated parts in the tank.

So are you suggesting to leave the fuel distributor connected and let the system run a complete cycle more or less?

[David T]

So are you suggesting to leave the fuel distributor connected and let the system run a complete cycle more or less?

Yes, unless you know it is so messed up that it has to be disassembled to be cleaned up.

[DMCMW Dave]

It's extremely important to flush the solvent out all the way through the injectors with fresh gas when you are done. If you leave any of the B12 (or the like) in the system it will damage internal rubber parts pretty quickly.

[TTait]

It's extremely important to flush the solvent out all the way through the injectors with fresh gas when you are done. If you leave any of the B12 (or the like) in the system it will damage internal rubber parts pretty quickly.

That was my original thought - I've done the reference procedure twice and have not had any issues, but I did bypass the FD, CPR, injectors, etc. and I flushed with gas immediately after to get the B12 out of the accumulator.

[AZ-D]

Sorry to revive a dead thread, but I though it better than starting a whole new one. At this point.. I am just trying to see if I can get the car to fire up before I move onto the next thing. If it won't fire, no reason to worry about anything else yet.

I pulled the lines from the pump off the hard lines at the front and it is a little gummy looking inside the end of the hard line. I took a small pick and its soft brown material that comes off easily. I don't think I need to get as involved as the "How to" suggests and it seems like just running some fresh gas thru the line would clear it up significantly, but I don't want to push any of that material to the distributor.

Can I disconnect the hard line at the fuel filter and jump the RPM relay to pull fresh gas through the line and see how it comes out? Or is there some other version of that to get the line clear?

[Bitsyncmaster]

Can I disconnect the hard line at the fuel filter and jump the RPM relay to pull fresh gas through the line and see how it comes out? Or is there some other version of that to get the line clear?

Yes that would work for the pump feed line. You may also want to flush the return line. Maybe do both at the same time with a hose on the disconnected feed line to the disconnected return line. Then disconnect the return line at the tank and pump till the gas runs clean.

[David T]

Before cleaning the lines you should get the tank as clean as you can and after you flush everything, clean the tank again.

[crbritt83]

Patience is key. One crank attempt that pulls any sludge through the system will cost you significant time and money. Fight the urge that says “I think it’s clean enough to try.” You will be very happy you did as you learn more about the car and read the stories of folks who cranked with bad gas and sludge after years of sitting.

[AZ-D]

Yes that would work for the pump feed line. You may also want to flush the return line. Maybe do both at the same time with a hose on the disconnected feed line to the disconnected return line. Then disconnect the return line at the tank and pump till the gas runs clean.

Just to clarify, fuel runs from the line on the bottom of the filter and exits to the engine through the top correct? Also, my thought was to keep the return line out of the tank and just run it into another container to make sure stuff stays out of my clean fresh tank. Is there some kind of diagram on here that shows the directional flow of fuel through the lines? I'm not exactly sure here I would tap into the return line at the same time.

After I flush the feed line to the fuel filter, can I do the same thing with the line from the filter at the fuel distributor? As in disconnect the line at the distributor and jump the relay to push anything out of that section too.


Before cleaning the lines you should get the tank as clean as you can and after you flush everything, clean the tank again.

The tank was surprisingly clean, but I pulled everything out and did a full cleaning regardless and replaced the baffle screen and hoses inside. Good call on cleaning after as well.


Patience is key. One crank attempt that pulls any sludge through the system will cost you significant time and money. Fight the urge that says “I think it’s clean enough to try.” You will be very happy you did as you learn more about the car and read the stories of folks who cranked with bad gas and sludge after years of sitting.

I am currently fighting that urge of clean enough. Once I peaked inside the end of that line I realized I need to go further. This car has not been sitting for very long so its not as bad as it could be. The car has 98k on it so I am hoping for some good results when it comes to start up time.

[AZ-D]

I removed the original return line hose from the hard line near the pump. It seems like the hard return line is blocked. I can not stick my poker tool into the line like I can with the feed line. It will only go about a half inch inside.

Can anyone elaborate on this part of the original referenced ::How to::

""Now, don't flush the fuel distributor, instead go to back to the engine area and locate the fuel feed and return lines at the distributor and disconnect them. These are large banjo fittings on the ends of the hoses, don't think about trying to disconnect them. Instead put a fender washer and rubber gaskets onto your 1/4" bolt and slide on one bango, the the other, then another rubber washer and fender washer, finally the nut. The fuel will flow, but it also will leak. Set this up so it cannot drip or run down the lines and drip, and get the connection into the second small tub. keep an eye on it during the flushing process, especially the first time you turn on the cheap pump.""

It's saying to disconnect the feed and return from the distributor, but do not remove the banjo from the line correct? Then, the bolded part is what I don't understand the most. I am supposed to basically bolt the 2 banjo fittings together?

Does anyone have pictures of what this is supposed to look like? A visual how to of this process on here somewhere maybe?

[Ron]

$.02

If you want to fire it up, disconnect the fuel pump and use starting fluid....

Gummy deposits or a blockage in the lines indicates that you should remove the lines and clean them one at a time -- Anything else is asking for it!
That said, if you want to blow them out with air, you can get nuts to fit the different size banjo bolts. Put a flat washer on the banjo bolt (to keep from scaring the banjo), then the banjo, another flat washer, and finally the nut. Then blow air into the end of the banjo bolt....

You asked about the flow: Pump -> Filter -> FD -> then simultaneously: 6 injectors, CSV, WU/CPR, CSV. The WUR/CPR and FV have return lines back into the FD. These two return lines (and the main return) connect to the two rearward, passenger side ports on the FD. The two ports are connected together inside inside the FD. This is why it would be hard to flush the lines following the flow. E.G. If you disconnect the line at the WUR/CPR feed port and push fuel/air through the FD, trash and fuel can also flow backwards through the WUR/CPR return line. That would mean yet another place to catch fuel and contaminating the WUR/CPR...

FWIW- Unlike carb systems, there is no such thing as being too "involved" when it comes to cleaning K-Jet fuel lines.

[AZ-D]

$.02

If you want to fire it up, disconnect the fuel pump and use starting fluid....

Fuel pump is currently disconnected. I have not reinstalled the tank yet. What is the benefit to using starting fluid? And how does that even work?


Gummy deposits or a blockage in the lines indicates that you should remove the lines and clean them one at a time -- Anything else is asking for it!
That said, if you want to blow them out with air, you can get nuts to fit the different size banjo bolts. Put a flat washer on the banjo bolt (to keep from scaring the banjo), then the banjo, another flat washer, and finally the nut. Then blow air into the end of the banjo bolt....

That makes sense. At this point I should probably just buy all new fuel lines cause the original ones are on the car and I will have to buy new ones eventually regardless.

What is your recommendation for clearing the blocked hard return line headed back to the pump?

[Ron]

Fuel pump is currently disconnected. I have not reinstalled the tank yet. What is the benefit to using starting fluid? I only mentioned it because you said, "If it won't fire, no reason to worry about anything else yet."
People roaming the junk yards looking for an engine use it all the time -- Helps identify if one knocks/smokes/etc.


And how does that even work? Check this out:

https://www.youtube.com/watch?v=XnIRdKZId3s

FWIW, I wouldn't run it any longer than it takes for it to prove itself (seconds).



What is your recommendation for clearing the blocked hard return line headed back to the pump?I'd try Acetone (or Xylene), in both ends, and let it soak overnight. Then get try to blow it out with the air compressor. If that didn't do it, I'd replace it.
I wouldn't get either near non-metal parts in the fuel system.