Hello! I've been working on my fuel tank for my XJ40 1989 for some days now, the thing was that its was clogged, filled the whole tank with water but noting came out, only out of the fuel return outlet it started flowing when the tank was full. My idea was of just removing the hose to the other side of the outlet that goes to the fuel pump and skipping the plastic tank in the tank because it seems to be in there its clogged and this seems to be the most easy solution for me cause its hard to find another tank over here. But now i got flow through the outlet going the fuel pump and the return seems to work fine to, i'm just curious about if there is some kind of check valve at the return line in the fuel tank of an 1989 XJ40, because i can blow air in through the return outlet but its not going through like free flow, need to blow as much as when you blow in a balloon and if you suck instead of blowing its sounds like a flap is closed and you cant suck so it seems like it's may be one there?

So i guess there is a check valve att the return line in the tank for some reason? Read something about it somewhere and someone said it was so but i just wanted to be sure so that i don't put my tank back and it's still faulty

This is not my tank but i have the same outputs, the big one is the fuel return an the smaller one goes to the fuel pump, if i now have'nt got it totally wrong haha..



Best regard!

 

Hi Simon,

I am not certain about the 3.6L XJ40s, but the 4.0L cars do have a check valve in the fuel return line port in the tank which is shown in the diagrams in the Technical Guides, so it is quite likely that your car has a non-return valve there as well. As long as returning fuel can make its way past the check valve into the tank, you probably won't have a problem. If the check valve allows fuel to drain out of the tank into the fuel return line that wouldn't seem to be too much of an issue since it's a closed system. The only serious problem I can think of would be if the check valve stuck and prevented returning fuel from re-entering the tank.

Your car also has a check valve on the outlet side of the fuel pump which works in concert with the Fuel Pressure Regulator (FPR) to maintain pressure in the fuel rail. Failure of one or both of these components can contribute to hard starting, stalling, accelerated wear of the fuel pump, etc.

Cheers,

Don

 

Hmm okey! It does really seem to be one in my tank, today i put a waterhose with just a smal amount of water going through it, not a hard beam at all just like it was pouring a little and put it inside the returnline and it made it through so it seems like its working, if that smal amount of water made it through so easy the petrol is going to, so it seems everything is in order and thats an relief, going to mount it in this weekend and then i'll see :-)

 

Wash the tank out with alcohol or add a cup of alcohol to get rid of any remaining water perhaps?

Larry

 

Yes of course:-)