Fuel starvation

[Bat21]

I'm currently in Morocco and are having problems on the long steep hill climbs, the motor struggles to get above 2,000 rpm and almost stops completely if the climbs are long enough.....

Following on from this post last September while in Morocco.

It only seemed to occur on one day and 5 months on it never happened again.

The advice at the time seemed to point towards a blocked tank filter so today I removed the kit from the back and set about sorting this out.

I carefully removed the plate from the top of the tank and lifted the fuel gauge sender and pickup, there was no filter on the end of the pickup tube.... it was sitting in the bottom of the tank. It was certainly not knocked off during removal so I suspect it has been there for some time.

So now the question is.... what was causing the fuel starvation?

 

[karl webster]

I guess it would have been the fuel filter then paul or maybe air getting in.

 

[Bat21]

It's an odd one Karl.

Fuel filter was replaced just before the trip so had only done maybe 2,000 miles.

Not sure where the air would have been getting in....

 

[Chris]

I can't give you a positive definitive on this one, but some things I have observed.

I fitted a clear fuel filter in line once and nearly passed out when I saw how much fuel goes through the line when the engine is revved to driving speed. Yes, I know that some goes back to the tank, but the volume was incredible. Hence the 12mm ID pipe.

I think the tea strainer comes off in the tank when people blow an airline down the fuel pipe at the bulkhead. So maybe someone has had this issue before?

I fitted a second (back up) filter to mine and in Morocco decided to switch over to it one day. It was a tractor filter thing and supposedly capable of handling the flow. I couldn't get past 50 mph. I had to swap back. Maybe after market filters don't have the same flow capacity. Maybe they do. But certainly it seems any restriction over OEM spec seems to starve the engine. That was with a pusher pump working too.

Air getting in? Well we do know the primer pump diaphragm is a weak point and gets holes in it. If the fuel is struggling to come through then I guess air might be pulled in as an easier option. Perhaps altitude plays a part.

Like I say, not answers - just things I have come across which have had an effect.

 

[Grimbo]

Seeing as the filter was off the end of the pipe check that something isn't in the fuel line .

We once spent many hours trying to trace a fuel issue on a big bit of plant kit , it had new fuel filters and the lines were all clear it seemed but every now and then it would suffer fuel problems .

Eventually traced to a large grain of wheat that had somehow got sucked into the fuel line and due to gravity would only get sucked up against the orifice in a banjo bolt just before the first filter if max fuel flow was demanded for an extended period . Opening any part of the fuel system would let fuel drain away and suck the grain back down the pipe so nothing was ever visible , we had even blown back down the lines with an air line .
Only found when every fuel line was removed from the machine as a collapsing fuel line was suspected .

 

[Shayne]

Could a loose pickup filter in the tank not get sucked up back onto the pipe causing a blockage .

 

[Bat21]

A few ideas there thanks folks.....

Talking of air, what I have noticed sometimes when removing the filler cap there is certainly a vacuum in the tank and there is a whoosh of air as I remove the cap. Reading what Chris just wrote ref the amount of fuel that flows from the tank (okay so some returns) it sounds like air can not get back in quick enough..... should there be a breather hole in the filler cap? Mine is a JDM import and I'm pretty sure the cap isn't like the UK ones.

 

[Michael Montgomery]

Could be the fuel filter air primer leaking air......seen it before can't tell other than bypassing it straight to the fuel pump to test.

 

[chapel gate]

Could a loose pickup filter in the tank not get sucked up back onto the pipe causing a blockage .

Good call there shane, if it was sucked towards the pick up pipe end on it would restrict flow.

A few pumps on the hand primer would tell you if its that,(the primer)
If little resistance is felt and it doesnt stiffen up, it needs replacing.

 

[Chris]

Not a chance of the pick up filter being sucked back onto the pipe I'm afraid. More chance of winning the Lotto back to back for a whole year. The filter element actually floats. Took me ages to retrieve mine as it had got the other side of the baffles in the tank.

The tank has two breathers actually. One to let air in to make up the loss of fuel and one to let vapour out as temp in the tank increases. One is in the cap and the other is on the end of a rubber pipe tucked into the rear cross member area. It has a little filter canister on the end. You can check both. The tank is, according to the FSM, supposed to run under very slight positive pressure IIRC.

 

[chapel gate]

Not a chance of the pick up filter being sucked back onto the pipe I'm afraid. More chance of winning the Lotto back to back for a whole year. The filter element actually floats. Took me ages to retrieve mine as it had got the other side of the baffles in the tank.

The tank has two breathers actually. One to let air in to make up the loss of fuel and one to let vapour out as temp in the tank increases. One is in the cap and the other is on the end of a rubber pipe tucked into the rear cross member area. It has a little filter canister on the end. You can check both. The tank is, according to the FSM, supposed to run under very slight positive pressure IIRC.

Even if the fuel level was low?

 

[Bat21]

My filter element does not float, mine was sitting at the bottom of the tank and thinking about it there is a possibility that it could get sucked back onto the pickup tube.

Sounds like I need to seek out this breather tucked into the rear crossmember and check to see it is not blocked.

 

[Chris]

If that filter can get stuck on the end of the pipe again then you really should make sure you fill in the Lotto.

I'd certainly service the filler cap and check the little canister.

 

[chapel gate]

I can see no reason why there isnt a reasonable chance that the filter could be sucked against the pick up pipe.

 

[Chris]

Guys have a look at the end of the pipe and then have a look at the filter. Why are we having this ridiculous debate? Remember that the filter is actually a filter. So if it did get sucked up again the end of the pipe all it would do is act as the filter. The chances of somehow randomly orientating itself against the pick up, inside the baffled anti surge area and remaining there whilst the truck bashes about on the Moroccan roads being held there by the suction of the fuel pump which can't even self prime is just something I really can't believe. I would say it's far more likely that something got sucked up the pipe due to the absence of the filter on the end of the pick up pipe.

 

[Firewout]

I had something similar with my 24v cruiser. Engine shut off when at idle on a slope with the nose pointing up and also wouldn't start without priming on cold mornings. The engine just coughed once and then shut off. I replaced the suspected primer pump with no result. Replaced the acsd with a blanking plate and the problem was solved. Engine starts normally now even when it's freezing.
@ bat21: maybe air gets sucked in the pump of your cruiser as well. Easy to test.

 

[chapel gate]

Guys have a look at the end of the pipe and then have a look at the filter. Why are we having this ridiculous debate? Remember that the filter is actually a filter. So if it did get sucked up again the end of the pipe all it would do is act as the filter. The chances of somehow randomly orientating itself against the pick up, inside the baffled anti surge area and remaining there whilst the truck bashes about on the Moroccan roads being held there by the suction of the fuel pump which can't even self prime is just something I really can't believe. I would say it's far more likely that something got sucked up the pipe due to the absence of the filter on the end of the pick up pipe.

View attachment 140773

That filter needs a clean chris..

 

[Dave2000]

Seen a smarty tube lid in a Sierra fuel tank causing starvation in the past...go figure!

I have not read the complete thread but did the 3rd filter get cleaned? Or after fuel starvation did you try a cleansing agent? If you did this may have cleaned the 3rd (pump) filter?

Also on the end of the fuel stop plunger is a small rubber 'bung' that has on some models come adrift, the plunger lifts but the bung stays in place, so now blocking or restricting fuel flow.

I apologise if those suggestions have been suggested, just throwing it out there before shooting off to work.

Regards

Dave

 

[Bat21]

@ bat21: maybe air gets sucked in the pump of your cruiser as well. Easy to test.

Apologies for sounding dumb here but, how would I test that?

I have not read the complete thread but did the 3rd filter get cleaned? Or after fuel starvation did you try a cleansing agent? If you did this may have cleaned the 3rd (pump) filter?

Where is this 3rd filter Dave? Is it easily serviceable?

 

[frank rabbets]

There is a banjo bolt in the back of the pump. Easy to get off. Inside there there is a small filter in the form of a tube. Now this is not the inlet but it may cause problems if blocked. I think there is another one on the pump inlet. I had a quick look on mine but could not find it but if you've got a problem may be worth investigating.

With that filter profile it won't stick to the tube.