Bizarre Fuelling problem (bit of a long read, complex problem)

[Sprinter Freak]

Car - 1982 corolla

motor - 16v 4age bigport

problem - fuel starve/ leaking fuel/ pumps cavitating

occurs - Getting fuel starve on hard right hand drifts/corners when hot
-leaking fuel when hot, but not when cold :S
-lumpy uneven idle

Hey guys,


So im stumped with this one, its been an ongoing problem for 6 months or so and i can't work it out!

At the last AE86 drift fest, the fuel starve/surge started happening on tight right hand corners (thought it might have been fuel sloshing away from the pick up/sloshing to one side of the surge tank). The main fuel pump a Bosch 070 which runs after the surge tank was getting pretty loud after a few runs, it sounded like it was sucking up air.

After drift fest, i changed the 070 pump out for a fresh one thinking that was the problem. But at the next drift day it was still getting the fuel surge under hard right handers with a full tank of fuel. I then decided to change the lift pump to see if that would fix it.
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So i changed from a VL internal lift pump to an external carby 7psi box pump(changing the in tank pick up to stock uncut one). I also added a one way valve after the box pump so it wouldn't loose pressure, Incase thats what was causing it.



Then went and did a Wakefeild drift day recently, in the morning it seemed fine. No surging or loud fuel pumps.

Towards lunchtime it started surging again on right handers, i took it back into the pits. As i pulled up is was pissing fuel out from under the car (near where the new pump was installed) the pumps were both extremely loud as well, sounding like they were working hard.

I turned it off and let it cool down, the leaks stopped. I had a look over the rubber lines but couldn't see any obvious tears or splits, i did notice that the return line to the tank was a little kinked but, but not massively. I started the car again and the leak had stopped, i then filled the car with petrol incase it was low.

Took it out for a few more runs, seemed like it was running ok and the pumps were quiet but after 20 minutes it started surging again. Pulled it back into the pits and it was leaking again. I left it for the rest of the day, as i went to put it on the trailer it was hardish to start and there was no leaks :S it had also developed a very uneven idle, usually it sits just above 1000rpm and idles very constant. It was now sitting just below 1000rpm and bouncing a bit.

A few days after i tried to start it, again not easy to start. I couldn't get it to idle for the first few seconds, had to keep my foot on the throttle or it would die. It also felt strange, sputtering for a bit as if not getting fuel, then picking back up like it just got a enough.

Am going to change the plugs today and test how many amps/volts the pumps are getting.

Other then that what should i be checking/replacing?


Any help is much appreciated guys, am pretty lost as to what it could be at the moment.

Cheers

Ryan

[munki]

sounds like you are running your pumps while they are starved for fuel. This makes them hot and sad. You need a surge tank.

[Matt]

I'd start by replacing your fuel hose at the tank. You can do it without dropping the tank. Perhaps it is still carby hose and over time has been stretched by the pressure?

The efi hose which you can buy from repco. I put 2 efi hose clamps on the stock ke70 lines a few mm apart to ensure a snug fit and have never had issues. Plus the clamps are like $1ea

I wouldn't be surprised if you are leaking fuel, which in turn is not filling up the pump / making them loud / hot.

[Sprinter Freak]

sounds like you are running your pumps while they are starved for fuel. This makes them hot and sad. You need a surge tank.

I run a surge tank....

[Sprinter Freak]

I'd start by replacing your fuel hose at the tank. You can do it without dropping the tank. Perhaps it is still carby hose and over time has been stretched by the pressure?

The efi hose which you can buy from repco. I put 2 efi hose clamps on the stock ke70 lines a few mm apart to ensure a snug fit and have never had issues. Plus the clamps are like $1ea

I wouldn't be surprised if you are leaking fuel, which in turn is not filling up the pump / making them loud / hot.

when i replaced the lift pump i used fresh Gates EFI hose and clamps through out :S

hmmm i think i need to pull all the lines off and check them thoroughly, possibly pressure test the pump to check the seals aren't faulty.

[Matt]

Do u have access to a fuel pressure tester? I'd be measuring that.

If you are leaking fuel at the tank, tighten the clamps there. Its really the only spot they can leak from.

[Matt]

Blow the lines out with compressed air too whilst at it. It can dislodge crap causing poor fuel flow

[Javal]

Are you running in-line fuel filters? I've had struggles before with debris from the fuel tank blocking the fuel filter for the lift pump. From the sounds of things your issue is on the lift pump side, thus the surge tank isn't being sufficiently filled and the efi pump is starving.

[Jim621]

So is the lift pump plumbed straight into the main pump? or through a surge tank?

[Javal]

So im stumped with this one, its been an ongoing problem for 6 months or so and i can't work it out!

At the last AE86 drift fest, the fuel starve/surge started happening on tight right hand corners (thought it might have been fuel sloshing away from the pick up/sloshing to one side of the surge tank). The main fuel pump a Bosch 070 which runs after the surge tank was getting pretty loud after a few runs, it sounded like it was sucking up air.



sounds like you are running your pumps while they are starved for fuel. This makes them hot and sad. You need a surge tank.


I run a surge tank....


So is the lift pump plumbed straight into the main pump? or through a surge tank?

ITT: nobody who can fucking read.

[Skylar]

Are you running an AJPS surge tank? From memory, the way they mount puts the tank outlet to one side and is more likely to starve when cornering one way compared to the other. I don't remember which way it was.

Are you running the rail return to the surge tank or the fuel tank?

Is the surge tank hot when it does this? Crazy hot to the point of vapour locking?

And the leaks... I have no idea. Where is it actually coming from? Hairline crack in the surge tank that expands with heat and lets fuel out?

[Sprinter Freak]

Are you running in-line fuel filters? I've had struggles before with debris from the fuel tank blocking the fuel filter for the lift pump. From the sounds of things your issue is on the lift pump side, thus the surge tank isn't being sufficiently filled and the efi pump is starving.

Theres a filter the screws onto the carby lift pump, that was new with pump install. Theres another one just before the engine, but is only 5000km old. Maybe your right, this pump might not be strong enough to keep the surge filled. Might see if i can borrow a pressure test kit off someone and see what its getting at the main pump.

[Sprinter Freak]

Are you running an AJPS surge tank? From memory, the way they mount puts the tank outlet to one side and is more likely to starve when cornering one way compared to the other. I don't remember which way it was.

Are you running the rail return to the surge tank or the fuel tank?

Is the surge tank hot when it does this? Crazy hot to the point of vapour locking?

And the leaks... I have no idea. Where is it actually coming from? Hairline crack in the surge tank that expands with heat and lets fuel out?

Nah I'm just running a 2 litre in boot surge tank. That is another thing i was thinking could be happening, as its only on hard right handers it surges (when the fuel is sloshing away from the main pump.

yea I'm running the return line from the front of the car to the number 2 barb in the picture.

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Barb 3 is the feed from the tank that the lift pump plumbs into

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Number 1 barb goes to the return line on the fuel tank

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Barb number 4(not labeled) runs in line with the main pump goes to the feed line for the engine.



I didn't feel the surge tank to see how hot it was when i got off the track, next event i will check it out.


I found out what the leaking was coming from, there was a small split right at the end of the breather line for the tank. Couldn't see it till i dropped the tank, so no more leaks :)

[Sprinter Freak]

Heres a video of the what type of noises the pumps are making, to me they don't sound right. Right at the start as i get close to the main pump is sounds like it cavitates for a second.


http://vid1081.photobucket.com/albums/j354/RyanRicho/20140922_130229_zpsirjr8mnl.mp4



What Lift pumps is everyone running? What psi rating are they to and how many litres per minute do they flow?

[Sprinter Freak]

Im using one of these as a lift pump, paired with a bosch 070 main pump

http://www.ebay.com.au/itm/FACET-FEP12SV-ELECTRIC-FUEL-PUMP-12V-12-VOLT-UNIVERSAL132-LPH-7PSI-NEW-PRESSURE-/300839526289 (http://www.ebay.com.au/itm/FACET-FEP12SV-ELECTRIC-FUEL-PUMP-12V-12-VOLT-UNIVERSAL132-LPH-7PSI-NEW-PRESSURE-/300839526289)

Supposed to do 132 litres per hour and up to 7 psi, is this too small?


Also been reading into vapour lock, could it be possible the 070 is too powerful for the standard fuel pressure regulator? would getting rid of it and going a sard adjustable unit possibly help?

[Matt]

Disconnect the vacume line off your pressure reg to test it. Idle should be effected

[Sprinter Freak]

i swapped it out for a sard adjustable one, just incase the high fuel pressure was putting strain on the pumps. Seems to run better with the adjustable one, not sure whether it will fix the surging problem, will just have to try it out and see.

But surprisingly i couldn't get it to anywhere near stock fuel pressure with the sard FPR. Stock fuel pressure for 4age's varies from 35psi to 38psi, the gauge on the FPR was sitting at 300kpa/43.5psi and i couldn't get it to sit any lower no matter how much i adjusted it.

http://www.ae86drivingclub.com.au/dcimages/5/1/8/5/540729.jpg (http://s1081.photobucket.com/user/RyanRicho/media/Screenshot_2014-09-23-16-19-39_zpszwnnntg8.png.html)

[Matt]

Possibly a blocked / restricted return line . Run the return into a jerry can as a test

[Javal]

Theres a filter the screws onto the carby lift pump, that was new with pump install. Theres another one just before the engine, but is only 5000km old. Maybe your right, this pump might not be strong enough to keep the surge filled. Might see if i can borrow a pressure test kit off someone and see what its getting at the main pump.

Pressure don't mean shit without flow. You can have a restricted line and still have good pressure but fuck all flow.

[Sprinter Freak]

Possibly a blocked / restricted return line . Run the return into a jerry can as a test

Could be, will give that a go and blow out the lines incase theres any muck in them.


Pressure don't mean shit without flow. You can have a restricted line and still have good pressure but fuck all flow.

yea true psi isn't a measure of how much flow there is.