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Help fuel line bubbles

ok i just changed my fuel filter yesterday, ran fine all day. today i was driving on my way to get a rock chip repaired, i was siting at a stop light and it turned green, i started to excellerate and it started to bog down i thought it was going to die, i thought i just pulled the clutch out to fast, but it did the same thing at the next light. i noticed i was low on gas, so i went and filled up thinking that mabey it was lower than i thought, or the gas gauge wasn't acurrate, i filled it up and started the engine it idles fine, i start to pullaway and it does it again, so i flip around park and look in the engine bay. and there are lots of air bubbles going through the line. i couldn't see any leeks or smell gas from anywere, it is pretty warm today, first time in a while, the fuel pump has been relocated to the front under the gas tank. looking for suggestions.... did i just run to low on gas and suck in some air that is stuck, my fuel pump does make some pretty loud buzzing sounds, could a seal in the pump be going??? I CANT AFFORD A NEW PUMP RIGHT NOW!!!!! help please.. or could a fuel injector just decided to start leaking alot?
Old 04-12-2006, 03:01 PM
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Which line?

1.) The supply from the pump to the pass side fuel rail?

or

2.) The return line from the pressure sensor across the back of the engine?
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1973 Chalon with 2.4T MFI (Schlitzalom)
All my 4 cylinders are gone
Old 04-12-2006, 03:39 PM
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it looks like it is just the return line, but i'm not sure if i can actually see through the sending line
Old 04-12-2006, 03:42 PM
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I had a '74 that would constantly show bubbles in the return line and ran very well.

You need to put a pressure guage on the drivers side fuel rail, before the pressure regulator (there is generally a 7mm tap there or a line going to the cold start valve...I don't know what year your car is) and measure the fuel pressure to the system.

You could be sucking air if the connections to your fuel filter are not tight.

You might want to try blowing back thru the suction line in case the sock in the tank is clogged and not allowing fuel to flow readily.
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1974 914/6 conversion with 2.7L (The Grey Ghost)
1973 Chalon with 2.4T MFI (Schlitzalom)
All my 4 cylinders are gone
Old 04-12-2006, 03:50 PM
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Also check for a kinked fuel line somewhere. That's how my car behaved when one of the under-tank hoses had a kink in it, because I left the hose too long when I replaced it.

--DD
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Old 04-12-2006, 07:31 PM
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Yup. listen to Scrappy

And Dave...

What did you just do?????huh????? huh???

Take alook underneath where the fuel filter is...make sure all the lines are happy, and not kinked at all....

Rich
Old 04-12-2006, 07:34 PM
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i was looking at things a little more carefully, and my fuel pump makes a load buzzing right before the fuel slows or the pressure drops causing, if i'm at idle for my idle to jump for a sec and then go back down, but if i am accelerating it boggs it down. do you think my fuel pump could just be going out, kind of getting hung and dropping fuel pressure. its just the timeing of the noise in the fuel pump that is making my think it is the fuel pump. and i think that would by why it looks like there are more bubbles, because the fuel slows. any thoughts anyone??
Old 04-14-2006, 12:37 PM
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I'd check for a kinked fuel line--the pump noise can change when it gets "starved" for fuel to pump. I'd also think about the fuel filter (did you install it in the correct direction?) and the fuel strainer sock in the tank.

--DD
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Old 04-14-2006, 01:17 PM
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i don't see any kinked lines. i did leave them alittle longer when i replaced them so i could pull the tank without with out disconecting anything.... i pointed the flow arrow on the fuel filter the same way the old one was. the line comeing into the back of the fuel filter is bent a little sharp but it isn't closed off.
Old 04-14-2006, 01:36 PM
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Try un-bending it. It doesn't have to be closed off to be a problem...

--DD
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Old 04-14-2006, 03:49 PM
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it didn't help, i pulled the tank out and set it up higher but still level so i could see all the lines, none were kinked and i even held the one to the fuel filter straight, and it still did it.

do you think it could just be the pump?? or does that not sound like the pump?
Old 04-14-2006, 10:36 PM
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Is this a 3 port pump? It sounds like the return port vibrating on and off. That also shows as air in the delivery side. I haven't figured out what causes it but I suspect any air in the system. I took the pump out and put it in an test jig and just started working right again. Check for leaks and kinks.
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Old 04-15-2006, 06:12 PM
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yes it is the 3 port and it does feel like it is comeing from the return, but there is no air in the delivery side of the engine bay just the return. and i can't find a kink anywhere. i'm really getting frustarated with this. the bogging seems to get worse the longer the car is on though
Old 04-15-2006, 07:05 PM
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where can i get a fuel pressure gauge that i can hook up to my fuel rail to check and set my fuel pressure??
Old 04-15-2006, 10:02 PM
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The fuel pressure guage I have didn't connect easily to the port. I had to T it in between the rail and the pressure regulator.

Sad news is that only one of my two pumps recovered from this state. The other is toast. We really need a rebuild kit for these pumps. The pump itself is bullet proof but the rubber, particularly the seal on the pop off has a limited life.
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Old 04-16-2006, 09:03 AM
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i actually had 2 pumps, when this one started having really bad problems, i swaped it for the other one i had, it leeked like crazy from the motor housing. so i took them both apart, swaped things that looked less worn tryed to clean out the motor housing (not the pump housing) without opening it, a few little chunks of things came out. i ended up swaping the actual port part of the 2 pumps, i noticed that on the bottom side of the port peice the return opening was much bigger on my second pump. not sure why? i thought they would all be the same. anyway i put it back together, and hooked it up, started right up and was ten times quiter than the old one. i thought that i had fixed it, i leav our shop and it drove so much beter i was racing around a little, first corner i take hard, as i come out of it it boggs down again, i just about screamed, so i drove it home tested it the next day, the bogg down still doesn't happen untill the car has been running for a while. but it happen more often, but not as severe, so i just ordered a new pump praying that is all that is wrong. (by the way, there were no more bubbles in my fuel line any more but they slowly krept in after about a day, the problem doesn't seem to change with the amount of air bubbles.)

Last edited by Jbagel2; 04-16-2006 at 09:44 AM..
Old 04-16-2006, 09:35 AM
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where did you get that gauge. my problem is that i can't find one that has more then just 10's marked on it, i want to find a more accurate one.
Old 04-16-2006, 11:42 AM
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I don't remember any more... It's been quite a few years. The gauge is a small VDO with the port on the back, and it seems pretty good... I bought two, just to have one as a spare, but either I loaned the spare out or I just can't find it.

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Old 04-17-2006, 06:29 AM
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so being that i replaced the pump that leads me back to daves suggestion, kinked fuel line. but i am haveing a very hard time finding were they might be kinked, i found one place that was a really bad kink, about an inch below the gas tank on what i think is the supply line. and i cut it as short as i could and still be able to remove the tank, are there no other problems besides a kinked line that could be doing this
Old 04-19-2006, 08:36 AM
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Did it run fine before you decided to mess with the filter?
then it wqould be one heck of a coincidenc that something actually died. More like you messed something up. and yes you have a kinked fuel line. get a mirror and a light and look up through the bottom hole from under the car. the hoses are only kinked when the tank is in. and yes it only may be a slight bend but a restriction none the less.

1st question I ask my techs. Was it broke before you tried to fix it?
Old 04-19-2006, 09:08 AM
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