Does fuel pump (injection) cut off if clogged?, YES i searched and read all 20 pages Options

[jsayre914]

On a bosh fuel pump (3 tit) does it cut out if it cannot get fuel?? I realize if it is intermittant it is probably a loose connection, loose or bad relay, loose pin on board, or dirty fuse on board, etc.

i am at work, and i am not so sure i will make it home tonight, i have a few tools, but no electrical stuff with me. i was wondering ....

what would the pump do with good power and a clogged line??


i made it half way to work and the pump cut out 3 times within 1 min, then dead. i pulled over checked the pump and all connections tight. i tried to start it 4-5 times, heard the pump run for 1 sec then dead. crawled under and shook the filtre and banged on the pump. it started but would not idle. i then loosend the clamp holding the pump and turned it upside down. car started and kept strong at high idle but started to choke below 3500 rpm. I risked the drive into work, and made it idling between 3500 and 4500, it would start to cut out and i would downshift jump the rpm and it was ok again.

welcome to my life

[jsayre914]

without tools and time i cannot trouble shoot so much but,

i went out on my lunch break and swapped the relay with the headlight relay changed the fusses on the board and checked pin #13 has good contact as well as the plug on the pump. everthing is go.

fire her up she runs with a little misfire, take it around the block, same thing. pump starts to cut out at full load and or low idle. if i pump the gas a few times i can save it each time.
(IMG:style_emoticons/default/confused24.gif)

[underthetire]

ok, not sure I can help but...
If it won't idle and dies at full load i'd check the charging system. You didn't specify what year/injection you have. Without a pressure gauge you really are guessing at a fuel pump IMO. I would check the grounds under the plenum, unplug the air temp sensor on the plenum. The olnly way I can see a plugged line cause this would be a supply line/filter. The other side just goes to the injectors and pressure regulator and back to the T fitting on the pump and back to the tank. It could be the pressure bypass valve on the pump went bad (IMG:style_emoticons/default/confused24.gif)

[jsayre914]

ok, not sure I can help but...

yes you can, thanks (IMG:style_emoticons/default/smile.gif)

If it won't idle and dies at full load i'd check the charging system. You didn't specify what year/injection you have.

It chokes at any rpm when the pump stops, no lights come on in the dash, and if i goose it a few times it catches again. The fi is a 74 1.8 l-jet.

Without a pressure gauge you really are guessing at a fuel pump IMO.

i have an inline fuel pressure guage, it reads about 30psi, when the car dies it reads zero, i cant see it fluctuate because i am in the drivers seat.

I would check the grounds under the plenum, unplug the air temp sensor on the plenum. The olnly way I can see a plugged line cause this would be a supply line/filter. The other side just goes to the injectors and pressure regulator and back to the T fitting on the pump and back to the tank. It could be the pressure bypass valve on the pump went bad (IMG:style_emoticons/default/confused24.gif)

i will change the filtre if and when i get home tonight, that was my original plan. not sure about a bypass valve or where that would be.

thanks for the ideas
(IMG:style_emoticons/default/beerchug.gif)

[jsayre914]

Hey,

does anybody have a fuel filtre to drop off at the karmic connection tonight?

(IMG:style_emoticons/default/biggrin.gif)

[underthetire]

Ok, L-jet makes more sense. I think those have a little flapper thingy inside the injection system to turn the pump on if I remember reading correctly. The bypass is the third nipple on the fuel pump.

[Cap'n Krusty]

Clogged filters are rare on our cars. They will NOT cause the pump to stop. It'll keep running until it burns itself up. If this is your L-jet car, check the inlet air boot and any other possible air leaks. The boot is NLA, and has been for years. The airbox will shut off the pump if there's not enough air flow going past the vane. Look at the TWO oil cap gaskets. They should both be intact and functional.

Report back.

The Cap'n

[jsayre914]

Clogged filters are rare on our cars. They will NOT cause the pump to stop. It'll keep running until it burns itself up. If this is your L-jet car, check the inlet air boot and any other possible air leaks. The boot is NLA, and has been for years. The airbox will shut off the pump if there's not enough air flow going past the vane. Look at the TWO oil cap gaskets. They should both be intact and functional.

Report back.

The Cap'n

if the clog will not cause the pump to stop, then i have an electrical problem, or a flapper problem as you said. both oil cap gaskets are brand new, and all vacume lines are brand new. i inspected that huge rubber pipe and washed it good befor putting it back on few weeks ago. Everything is super tight. i have the idle screw all the way in and i can idle just under 1000 smoothly. yesterday.

today is a different story.

i did a different search and found more possibilities. cht wire broken, grounds under plenum came loose, coil has turned around and grounded a wire? i will check these also, before jumping in for my 65mile ride home tonight. (IMG:style_emoticons/default/idea.gif)

[underthetire]

i have the idle screw all the way in and i can idle just under 1000 smoothly. yesterday.

Sounds like a vacuum leak to me. I don't know of any that would have the idle screw all the way in and idle at 1K.

[jsayre914]

i have the idle screw all the way in and i can idle just under 1000 smoothly. yesterday.

Sounds like a vacuum leak to me. I don't know of any that would have the idle screw all the way in and idle at 1K.

please explain...

i thought this was the norm. if i back the screw one full turn the idle goes up about 500rpm and again if i turn 500 rpm etc. is that not normal??

[r_towle]

i have the idle screw all the way in and i can idle just under 1000 smoothly. yesterday.

Sounds like a vacuum leak to me. I don't know of any that would have the idle screw all the way in and idle at 1K.

please explain...

i thought this was the norm. if i back the screw one full turn the idle goes up about 500rpm and again if i turn 500 rpm etc. is that not normal??

Yes that is normal. its actually perfect...at least the idle screw part is.

When you turn on the key the pump runs for 1.5 seconds, then shuts off.
That is how Djet works. It comes on again when the motor is running.

It sounds to me like you have an elec issue, not a fuel issue.
Ignition wire loose, positive wire to coil loose,

Ignition switch or plug under dash going up into the steering column is loose.
Pull relay board cover...pull all the plugs and volgate regulator...
Reseat all of them.
Clean both positive and negative battery terminals..clean the main power wires (the smaller red ones) that feed the ignition and the accesories)
Make sure your coil is not touching ground.
Check all three wired going to the coil for breaks and shorts.

You need to run through ALL the wires to wiggle them and see what is loose.
I chased an issue for days and it was a loose wire that somehow got inside the distributor and was shorting things out...hard to explain...I rebuilt the distributor to find it.

Rich

[jsayre914]

i have the idle screw all the way in and i can idle just under 1000 smoothly. yesterday.

Sounds like a vacuum leak to me. I don't know of any that would have the idle screw all the way in and idle at 1K.

please explain...

i thought this was the norm. if i back the screw one full turn the idle goes up about 500rpm and again if i turn 500 rpm etc. is that not normal??

Yes that is normal. its actually perfect...at least the idle screw part is.

When you turn on the key the pump runs for 1.5 seconds, then shuts off.
That is how Djet works. It comes on again when the motor is running.

It sounds to me like you have an elec issue, not a fuel issue.
Ignition wire loose, positive wire to coil loose,

Ignition switch or plug under dash going up into the steering column is loose.
Pull relay board cover...pull all the plugs and volgate regulator...
Reseat all of them.
Clean both positive and negative battery terminals..clean the main power wires (the smaller red ones) that feed the ignition and the accesories)
Make sure your coil is not touching ground.
Check all three wired going to the coil for breaks and shorts.

You need to run through ALL the wires to wiggle them and see what is loose.
I chased an issue for days and it was a loose wire that somehow got inside the distributor and was shorting things out...hard to explain...I rebuilt the distributor to find it.

Rich

i am reading this thread like a hawk (since i am jumping into the car at 8pm)

i used to have d-jet and yes it would always run for a sec, but now i have l-jet on a 1.8 and it does not ever run when you turn the key to the on position. i was worried at first but found out that was correct. it only runs when the key is to the start position.

however i have never had this problem before and im not sure how to do the flap test yet.

however... i did go out a few min ago and pulled the fuel filtre out and blew through it backwards as hard as i could and put it back on correctly. then poured a bag of kitty litter under my car. started it up, and did not notice any hesitation at all, but it is still parellel parked, i cant test it out for sure yet.
(IMG:style_emoticons/default/popcorn[1].gif)

[ericread]

I recenty had some significant fuel pump issues. So I printed out each of the pages from the following site:

http://members.rennlist.com/pbanders/FPChecklist_frame.htm

After going completely through the process, I found the fuel pump was, in fact bad.

In your case, I highly advise wiring the battery directly to the fuel pump. This includes both positive and negative wires. If the fuel pump does not run continuously, then the pump is FUBAR. If it does run, then start through each of the pages in the link. You will find your problem.

Eric Read

[r_towle]

i have the idle screw all the way in and i can idle just under 1000 smoothly. yesterday.

Sounds like a vacuum leak to me. I don't know of any that would have the idle screw all the way in and idle at 1K.

please explain...

i thought this was the norm. if i back the screw one full turn the idle goes up about 500rpm and again if i turn 500 rpm etc. is that not normal??

Yes that is normal. its actually perfect...at least the idle screw part is.

When you turn on the key the pump runs for 1.5 seconds, then shuts off.
That is how Djet works. It comes on again when the motor is running.

It sounds to me like you have an elec issue, not a fuel issue.
Ignition wire loose, positive wire to coil loose,

Ignition switch or plug under dash going up into the steering column is loose.
Pull relay board cover...pull all the plugs and volgate regulator...
Reseat all of them.
Clean both positive and negative battery terminals..clean the main power wires (the smaller red ones) that feed the ignition and the accesories)
Make sure your coil is not touching ground.
Check all three wired going to the coil for breaks and shorts.

You need to run through ALL the wires to wiggle them and see what is loose.
I chased an issue for days and it was a loose wire that somehow got inside the distributor and was shorting things out...hard to explain...I rebuilt the distributor to find it.

Rich

i am reading this thread like a hawk (since i am jumping into the car at 8pm)

i used to have d-jet and yes it would always run for a sec, but now i have l-jet on a 1.8 and it does not ever run when you turn the key to the on position. i was worried at first but found out that was correct. it only runs when the key is to the start position.

however i have never had this problem before and im not sure how to do the flap test yet.

however... i did go out a few min ago and pulled the fuel filtre out and blew through it backwards as hard as i could and put it back on correctly. then poured a bag of kitty litter under my car. started it up, and did not notice any hesitation at all, but it is still parellel parked, i cant test it out for sure yet.
(IMG:style_emoticons/default/popcorn[1].gif)

Ljet pump test.

Pull large rubber hose off the AFM unit so you can stick your finger in the AFM.
Turn key to run position.
Stick finger in AFM unit and open the door (you can see it if you look in the hole)
Pump will run till you let go.

Rich

[VaccaRabite]

You home yet?

Zach

[jsayre914]

Ljet pump test.

Pull large rubber hose off the AFM unit so you can stick your finger in the AFM.
Turn key to run position.
Stick finger in AFM unit and open the door (you can see it if you look in the hole)
Pump will run till you let go.

Rich

I did not have time to trouble shoot yet, but last night after i made it home (IMG:style_emoticons/default/cheer.gif)

i stopped at the gas station. I opend the air box, and looked up into the lid. i saw the flapper and i took a extra piece of vacume hose and slid it into the afm to hold the flapper open. i jumped into the car started it, and ran back to watch. the pressure guage read solid 30 for about 2min, then it started to stumble. 30....20....30....15.....20....5....0 the car died and i heard the fuel pump cranking away rrrrrrrr untill i pulled the hose and let the flapper shut.


(IMG:style_emoticons/default/idea.gif)


tommorow i will troubleshoot if i can get enough time.

[underthetire]

Could be the sock in the tank. Have you changed it ?

[r_towle]

Its either the fuel pump, or the fuel pressure regulator which is unique to Ljet...its a rising rate fuel pressure regulator.

Rich

[jsayre914]

Its either the fuel pump, or the fuel pressure regulator which is unique to Ljet...its a rising rate fuel pressure regulator.

Rich

tommorow, my plan is to replace the fuel filtre and then run a jumper to the fuel pump from the coil + lead. if it has any cutting or stumbling sounds it is the pump right. if it stumbles but the pump is continues sound. Then i have a clogged sock??

sound like a good approach?

[underthetire]

Not if what Rich says, rising rate regulator. I don't know the Ljets. I think you would need to plug the regulator, not start the car, and watch the fuel pressure for a few minutes.

Rich????