Oil & Fuel TC45D Fuel Vent Problem

[burtrl]

My TC45D is suffering from poor fuel flow. When I disconnect the vent line from the tee near the fuel filter fuel flow immediately improves. I have blown out the vent line several times which works for a short while then problem returns. The vent line is not kinked anywhere, and I have disconnected vent line at both ends and found it to be free of obstructions by blowing in it. The problem to me, seems to be inside the fuel tank. Does anyone have any ideas or experiences with this type of problem?

Thanks,

Ross

 

[jinman]

I would check the condition of your venting fuel cap. I would remove the fuel cap and see if that makes a difference when operation is erratic. Fuel return to the tank is through the top of the tank and fuel pickup is at the bottom of the tank. Trash would normally clog the pickup rather than the return line. The return is in the center-top of the tank where the fuel gage is located. I guess it's a remote possibilty, but your lift pump below and behind the fuel filter might also be failing. The "T" you speak of takes excess fuel from the injector pump and lift pump via the filter and returns it to the tank. This is part of the "auto-bleed" system on the Class III Boomers.

 

[Porkie]

I took my gas (diesel) cap off once and took an air hose and blew air into the end of the line that feeds the fuel filter and the diesel flowed much better after that. I always use a good fuel additive and try to replace fuel filters often. I ran the TC out of fuel once and did this hose thing as part of a process of elimination, when my TC wouldn't start. I ended up having to "bleed" the injector pump, which fixed the problem. My gage hadn't read empty but obviously, it wasn't accurate.

Sam

 

[SpudHauler]

It is a rare occasion, but I have seen where a fuel line or other rubber lines have come apart on the inside and plugged themselves. Usually occurred near a fitting or where they were forced onto a fitting and the inner lining was cut and became a flap. Caused all sorts of crazy unexplainable fuel and vent problems.
Just something else to check.

 

[jedjoe]

I have the same gas gauge system on my TC35, and after a good year or two of accurate readings, it's no longer all that reliable. Another TCN member recommended just topping off the tank after every serious use of the machine, which I now do myself and not had to stop in the middle of a job and bleed the darn injectors (which comes from letting m'Blue run dry...)! Saves on scraped knuckles and cursing, as well!

I once accidentally got some junk down into my tank on a refill, and had a heck of a time getting it out of the tank. Someone should make a post-production intake filter to sit inside the tank opening.....or has someone done that already?? If so, sign me up!

 

[jinman]

Someone should make a post-production intake filter to sit inside the tank opening.....or has someone done that already?? If so, sign me up!

Mr Funnel

It's a bit hard to use in our tank's position, but it does work. They sell them on Amazon.com.

 

[burtrl]

Thanks everyone for your input. The problem occurs regardless of the amount of fuel in the tank. I tried loosening the cap on the tank this weekend, but this did not help.

Jim, If I understand correctly, the line that I am blowing out is not a vent line, but actually a return line from the lift and injector pumps. The system would therefore function similar to that on a car where the fuel pump basically pumps more fuel than is required by the injection pump, and the excess is returned to the tank. If this is the case, I am starting to suspect, as you mentioned, that the lift pump may not be pumping enough fuel to the adequately supply the injection pump. Also the system has a check valve on the return line in case of roll over. Perhaps this is sticky as well, causing the lift pump to have difficulty overcoming the spring in the check valve (I am assuming that the check valve is closed unless the pump is pumping enough pressure to open the check valve). I think the next thing to check is the lift pump. Any suggestions as to how to test it.

Thanks,

Ross

 

[jinman]

Ross, I think the lift pump really only functions when the fuel tank is much less than full or you are driving up an incline. I'd fill the tank completely and then bypass the lift pump by putting a solid nipple between the input and outlet hoses. You might also try to backflush the pump in case it has some junk in it.

I called the fuel return line a vent line, but you and I are talking about the same line. It is a fuel return and the fuel cap contains a vent.

 

[burtrl]

Thanks Jim. I'll try that on the weekend and see what happens. If that doesn't help, I'll try disconnecting the return line from the check valve on the top of the tank. I'll let you know how this turns out.

Ross

 

[banjodunn]

G'day the lift pump is there to supply pos press to the inj pump some systems can run without them and some do not perform very well without them. Do you have a removable cover on the top of the lift pump these often hide gauze screens that often get overlooked and can block up. also as said check your fuel cap to make sure it is venting correctly



Jon