Fuel transfer pump

[kevoc Lurker Find all posts View Profile Close kevoc]

I need a bit of enlightenment from the more knowledgeable amongst those on this forum.

Recently I had the Fuel transfer pump replaced for the 150k service at a dealership. 2 weeks and 500k's later with half a tank of fuel showing on the gauge the low fuel light began flashing. The RACV attended and gave me fuel to make it to the servo. After inspection I found the breather hose on the main tank had not been replaced properly and was loose. Having a basic understanding how the transfer system works with the pump and venturi arrangement I cannot understand how a loose breather hose could stop the transfer of fuel and be the only problem. Long story short I took it back to the dealership who said they found the the hose wasn't clipped on properly however every thing else checked out fine. Having multiple issues with the workmanship of this dealership in the past I have no faith in anything they do or say, and after this issue is rectified will not be going back.

Another symptom it suffered was that when I did fuel up at the servo the fuel had to be trickled in taking about 15 mins to get 50 ltrs in, otherwise it would froth up. OK that I can understand being related to the breather hose but not the fuel transfer issue.

In peoples opinion, could the hose be the only problem or am I being fed a load of B/S from the dealer.

Thanks in advance
Kevoc

[ptommo59 Senior Member Find all posts View Profile Close ptommo59]

The Dealer if following the Warranty and Service Booklet should have Replaced the complete Fuel Transfer Pump Assembly at the 150K Service not just the under vehicle filter (which should have been done at the 140K Service so should still be OK until due for next replacement at 160K).

But yes, your symptoms are exactly right for a fuel transfer fault with the sub-tank still full and main approaching empty (which is why the gauge is still reading around 1/2) and full sub tank is blocking the filler neck breather (which makes it hard to put fuel in without blow back).

The loose breather hose is definitely not the cause so start with the Fuel Pump fuse and relay in the engine bay fuse box (check Fuse OK and relay clicks after about a minute or so of engine running switching on the transfer pump).

If that is OK then did they actually replace the pump? and could they have accidently plumbed the pipes to the incorrect points on the main tank as they are same size hoses and close together.(as if yes the venturi wont work which will cause your issue) or if hoses connected correctly did they check the pump was operational as it seems it isn't?

[kevoc Lurker Find all posts View Profile Close kevoc]

Yes that reinforces what I thought. I believe they did replace the pump assembly (or gave it an exceptional clean) as I check their work when as best I can when I arrive home, but without dropping the tank its hard to be certain. I did wonder if they left any other hoses off. Never occurred to me that the the hoses are the same size and could be mistakenly swapped. I took the car for a long run yesterday to get the tank well down below half and so far so good. They may have rectified the problem, however I will check the relay and fuse as its handy to know where they are.

Sorry I meant to say the pump was replaced not the filter.

Thanks ptommo59, you're input is much appreciated.

[RPP Senior Member Find all posts View Profile Close RPP]

If one or more hoses to the fuel breather valve (the one mounted under the cabin/above the rear diff) were loose/off then dust and dirt could be ingested.
This could clog the venturi circuit.

Next time you have the fuel pump (or anything else significant) replaced, ask the Dealer to give you the original one (for a spare). That way you'll know if they did the job.

[kevoc Lurker Find all posts View Profile Close kevoc]

Its sad to think you have to resort to having proof of the job being done, but yes that's a good idea. I normally discreetly mark filters etc to make sure that they are changed and not just cleaned. As I said the workmanship at this dealership is atrocious. The only reason I kept going back was convenience. Its walking distance to home. But never again.
Thanks RPP

[kevoc Lurker Find all posts View Profile Close kevoc]

Well it's happened again. Filled up at the servo with no problems and about 500k's later, same problem. Back to the dealer who has the car for 2 days, drops both tanks and checks both fuel sender units (shows me photos to prove the tanks came out). Everything tested fine electrically however he shows me photos of the breather located above the diff covered in crud and told me it was blocked, so he's cleaned and reinstalled it and said that is the problem. Seems coincidental that this causes a problem only after having the pump replaced. Just wondering if anyone has had this problem caused by that breather being blocked. Personally I'm still leaning towards a intermittent electrical fault in the pump but I suppose time will tell.

[404pug Avid PP Poster! Find all posts View Profile Close 404pug]

There is a long thread on the fuel pickup problem. That breather is one of 4 or 5 possible causes of the problem and should have been checked by them. Worth a quick check by all 120 and 150 owners if they have done any dirt road work.

[RPP Senior Member Find all posts View Profile Close RPP]

That hidden breather valve is not on Toyota's maintenance schedule. Ive had 2 Dealers tell me they never check them. I expect that almost every Prado on the road has a dust-clogged breather valve.
I replaced mine a few years ago and cut the old one open. The exhale circuit is bigger than the inhale circuit (you can barely poke a needle down the inhale hole). I decided that having the inhale opening clogged was all for the better since I occasionally drive thru deepish water and don't want the breather letting the tanks inhale a squirt of water. That was years ago, so far so good.

[ptommo59 Senior Member Find all posts View Profile Close ptommo59]

I think the reason the inhale side can be so small is the primary inhale breather for the tanks as they empty is the vent in the fuel cap (so the small one is only an safety/emergency inlet if the cap one is blocked to stop vacuum building up in the tanks and potentially causing other issues.
The larger one on the other hand will be the primary pressure relief valve during fuel expansion or if overfilled will release the overflow under the vehicle rather than potentially back into your face if the cap had to be removed under pressure.