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jvandyke

jvandyke

Luke Skywalker
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my Weber 32/36 equipped 1098 will sometimes behave like it's fuel starved when under load (cruising in 3rd/4th then accelerating).
I thought it was fuel pump so switched them out (electrics, ditched an SU for a Carter) it had no effect, so I replaced the filter right before the carb and it seemed to take care of it. Now it's back, so either;
a) there's crud in the fuel system plugging up my filter so that it can't keep the bowl fuel under high demand
b)the pump system itself can't cut it (both pumps were/are mounted in engine bay, I know I should move it back by the tank)
c) I'm on the wrong track and it's ignition related.

The solution is simply lay off the gas and wait or tickle the pedal, it seems to "catch up with itself" and I'm off again.

I can accelerate to redline in 1st or 2nd no problem but in 3rd or 4th it will induce the stuttering.

Thought I'd ask so I don't waste too much time fixing the wrong thing. Not too fond of running out of gas at high load, high rpm, could detonate, no?
 
If your sure you have cured the fuel delivery it may be the carb If this is happening at about 2 thirds throttle it is the secondary jetting.
could be its to rich or lean and on the secodary jets may even be the air corector tube is the fault.
Is that enough of a mouth full? Well fear not here is some info that will be help full on narrowing it down.This is one of the better articles on tuneing the DGV in plain speak.
https://dimequarterly.tierranet.com/articles/tech_weber_tuning02.html

Need some jets and a E tube or two? Find them on ebay reasonable.
 
I have the exact same problem. I just found that my pump cuts down to 1/2 pound of fuel pressure at times. I had purcolation in the bowl and vapor lock and all kinds of issues including running out of gas pulling hills. Gonna try a new fuel pump and see what that does for me.
 
The fuel inlet on my Weber is on the inboard side, should be swapped over the outboard probably, as it is I tied the water hose to hold it away from the inlet line but I've also since turned off the lines to and from the heater core. I should probably move the pump to the tank as they push much more effeciently then they pull, I did both of these to my old Opel and it helped fuel delivery alot. I've got the same issue with two different pumps though so I wasn't sure that was it. I'll have to do a flow test. I'm sitting at a coffee shop near work on the MG's first commute in, I'm REALLY nervous.
 
Someone check my math and my logic on this but.....
Logged some miles today. Had a couple episodes as mentioned above. Just pulled the line off the carb and ran the electric pump until it filled a cup's worth, took 36 seconds, so it would take 576 seconds (9:36) to fill a gallon (16 cups to gallon US) after an hour that's only about 7 gallons (US) per hour.
That stinks.
I'm not sure what volume a 32/36 needs but 7 gph isn't very much.
Guess I'd better move that pump back to the tank, eh?
Maybe re-do the line?
 
jvandyke said:
Someone check my math and my logic on this but.....
Logged some miles today. Had a couple episodes as mentioned above. Just pulled the line off the carb and ran the electric pump until it filled a cup's worth, took 36 seconds, so it would take 576 seconds (9:36) to fill a gallon (16 cups to gallon US) after an hour that's only about 7 gallons (US) per hour.
That stinks.
I'm not sure what volume a 32/36 needs but 7 gph isn't very much.
Guess I'd better move that pump back to the tank, eh?
Maybe re-do the line?
Click to expand...
Check the pressure too. That is what I did and it showed the low pressure. With a higher pressure it can get more fuel past the float and keep the bowl full. Mine would literaly almost run out of gas on a hill if I gave it too much gas, just backed off and give it a little and it catches back up.
 
jvandyke said:
Someone check my math and my logic on this but.....
Logged some miles today. Had a couple episodes as mentioned above. Just pulled the line off the carb and ran the electric pump until it filled a cup's worth, took 36 seconds, so it would take 576 seconds (9:36) to fill a gallon (16 cups to gallon US) after an hour that's only about 7 gallons (US) per hour.
That stinks.
I'm not sure what volume a 32/36 needs but 7 gph isn't very much.
Guess I'd better move that pump back to the tank, eh?
Maybe re-do the line?
Click to expand...
I checked mine with a quart jar on a high shelf and it worked out to about 9 gallon an hour so I thought I was good but the area their at that needle and seat is very small and you got to be able to force gas through there. Mine was only 1/2 lb of pressure. Find a gauge and check yours.
 
Am i thinking crazy or does 7 gal/hr seem like MORE than enough... let say you have it wound out in 1st gear, 5000 rpm going what 18 mph... that would be 18 miles/ 7 gallons,.. about 2 1/2 miles per gallon? seems to me... (and i don't really KNOW anything about these cars) 7 gallons an hour is P-l-e-n-t-y...


......."the book" say... 56 pints an hour.. for a MK III..oops thats imperial pints......67 US pints/hr..... so.. 7 gals is a LITTLE under...
 
Pythias said:
Am i thinking crazy or does 7 gal/hr seem like MORE than enough... let say you have it wound out in 1st gear, 5000 rpm going what 18 mph... that would be 18 miles/ 7 gallons,.. about 2 1/2 miles per gallon? seems to me... (and i don't really KNOW anything about these cars) 7 gallons an hour is P-l-e-n-t-y...


......."the book" say... 56 pints an hour.. for a MK III..oops thats imperial pints......67 US pints/hr..... so.. 7 gals is a LITTLE under...
Click to expand...
Yeah, 7 gal an hour is a lot for any vehicle to burn and a midget is not going to burn out a tank of gas in an hour. you are doing just what I did, flowing gas out of the hose. Flowing through the needle and seat will be much less than that. Plus you got the gas under low pressure trying to boil in there and creating pockets of vapor that can hold back the flow. I can relate man, I can't wind mine up tight for long or it starts running out, then I back off and just touch the gas for while and it straightens back out. I can feel it coming on at times and avoid the herky-jerky.
 
I've got a pressure regulator on the car, set at 4. Haven't confirmed that is accurate though, gas does not seem to come out with much pressure, just sort of dribbles in the jar. I've not ever heard of too little pressure on a Weber, too much yes. I guess it could be.
BTW this same pump, when on my Opel GT gave 16 gph when mounted in the engine bay, moved to the tank and increased to 3/8" fuel line, it gave 23gph. Guess I'd better just mount the bugger where it should be. (BTW filter between pump and carb is new, not that it couldn't be clogging up again already.....)
 
jvandyke said:
I've got a pressure regulator on the car, set at 4. Haven't confirmed that is accurate though, gas does not seem to come out with much pressure, just sort of dribbles in the jar. I've not ever heard of too little pressure on a Weber, too much yes. I guess it could be.
BTW this same pump, when on my Opel GT gave 16 gph when mounted in the engine bay, moved to the tank and increased to 3/8" fuel line, it gave 23gph. Guess I'd better just mount the bugger where it should be. (BTW filter between pump and carb is new, not that it couldn't be clogging up again already.....)
Click to expand...
That regulator is not going to raise the pressure, only lower it to whatever setpoint you have. If you have only 1 lb of pressure from the pump then the reg is going to only give out 1 lb.
 
Pythias said:
Am i thinking crazy or does 7 gal/hr seem like MORE than enough...
Click to expand...
Depends on the horsepower.

The brake Specific fuel consumption of an engine ranges from 0.35 to 0.6 lb/hr/hp. Average is about 0.5 lb/hr/hp.

This translates to:
The average engine, when putting out 100 hp, will require about 8 gallons of gasoline per hour.
D
 
Wow, that Dave always has a sharp pencil.
 
Just re-reading these posts and am wondering whether the problem is the tank itself? We're in Scotland tight now and every time I pour tea, when the teapot starts to run out the teabag gets into the spout and inhibits flow. Could you rig up a gas can "tank" and bypass the regular tank completely? This might point out if the issue is in front of or behind the fuel filter. I can't remember if you have a new tank? but my old one had a ton of sludge in it.
 
"so I replaced the filter right before the carb and it seemed to take care of it. Now it's back"

If that solved it doesn't it seem logical that is the problem - fuel filter is getting clogged? And if so than what is clogging it? Dirty tank?
 
I'd say...

a) Shake, or cut open that fuel filter... is it full of swarf?

b) Is the Carter a 'green' / 4070? If so, should be ideal... but yes, mounted down near the tank. I can certainly imagine that in certain high-load situations it might cavitate / have problems delivering enough fuel, if mounted high in the engine bay.

Or, as you say... might be the carb. The fact that fiddling with the filter seemed to fix things would suggest otherwise, though.
 
I also would clean the tank.
 
No idea if tank was ever touched up. Took several runs yesterday. No problem until 3rd run of the day, could barely keep her cruising on the level at 50 mph, finally slowed for a turn and then it took off and ran great, no reoccurrence, so it's very intermittent. I'd think if the filter was clogged it'd be more persistent. Oh well, I just created more pressing matters....tried to run a plug in the dipstick hole just to see if that's where a leak was...plug came out and I oiled the engine bay thoroughly! Might have to start a new thread on that one. This dipstick is weird.
Also I watched the speedo needle bounce and then fall to zero a minute ago......

The pump that is currently on there is of the solenoid variety.
Looks like this one.
Pump
Have the SU I took off, which is probably just fine too. Both were mounted in the front left corner of the engine bay, as high as the carb.
 
I would expect junk in the tank. Covers the pickup from time to time enough to shut it down or almost so then shakes off.
 
I'm inclined to think it's a tank/filter issue, too. I had the same problem. The car would run great around town, but as soon as I tried to push it to 55+ the filter would get completely clogged. I had a ton of sediment at the bottom of my tank. New tank + new filter = no more problems. If you have the old filter, blow some carb cleaner through it and see what comes out.

If it's the tank, then the filters will just continue to get clogged (at the worst times, I'll add). My second filter lasted all of ~40 minutes of drive-time before it got stopped up.

B
 
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