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cfroderman
Samba Member
Joined: November 23, 2021
Posts: 29
Location: Avon, IN
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 Posted: Sun May 15, 2022 9:23 am Post subject: Re: Official Fuel injection questions thread |
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77 VW Super Beetle Convertible - Engine Fire restoration -
Symptom - Slow build up of speed while driving - Poor power in all gears. It seems like the speed will gradually build up even with accelerator floored. Starts with no problems.
Replaced - All electrical, fuel and vacuum lines. Double checked VL connections to make sure they are correctly attached (within this thread).
Spark plugs & wires replaced. Distributor tests out OK. All electrical tests out OK on AFM. New fuel pump, fuel filter.
Idle at ~ 800 rpm and timed out to 5* TDC. Tested fuel pressure at 39 psi with engine off. I read that I should have tested it out at 3500 rpm. How important is the going to be?
I verified that the vacuum advance is OK by holding a vacuum (no leaks).
Any other items I should look at? |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51123
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Sun May 15, 2022 10:04 am Post subject: Re: Official Fuel injection questions thread |
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| cfroderman wrote: |
77 VW Super Beetle Convertible - Engine Fire restoration -
Symptom - Slow build up of speed while driving - Poor power in all gears. It seems like the speed will gradually build up even with accelerator floored. Starts with no problems.
Replaced - All electrical, fuel and vacuum lines. Double checked VL connections to make sure they are correctly attached (within this thread).
Spark plugs & wires replaced. Distributor tests out OK. All electrical tests out OK on AFM. New fuel pump, fuel filter.
Idle at ~ 800 rpm and timed out to 5* TDC. Tested fuel pressure at 39 psi with engine off. I read that I should have tested it out at 3500 rpm. How important is the going to be?
I verified that the vacuum advance is OK by holding a vacuum (no leaks).
Any other items I should look at? |
You say the vacuum advance holds a vacuum, does it move the breaker plate as well?, how about the retard side?, same results?
Fuel pressure doesn't have to be tested a 3500, but you could try applying vacuum to the sense hose with the engine off to watch for a pressure drop.
Does this car have a catalytic converter?
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cfroderman
Samba Member
Joined: November 23, 2021
Posts: 29
Location: Avon, IN
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| Posted: Sun May 15, 2022 12:36 pm Post subject: Re: Official Fuel injection questions thread |
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Both the advance and the retard side cause the breaker plate to move. It takes about 5-6 in Hg to cause it to move.
No pressure drop on the fuel side.
Tested the vacuum with the car running and revving the engine - It got up to 15 in Hg.
Checked advance (without vacuum) and it appeared to get to 30* at ~ 3000 rpm,.
No catalytic converter is present. I'm open to any other suggestions. |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51123
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Sun May 15, 2022 12:54 pm Post subject: Re: Official Fuel injection questions thread |
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Hmmmm...., fuel pressure should drop ~8-10 lbs when vacuum is applied, sure the pressure regulator's vacuum hose is connected?, is the hose wet with gas inside?
Other things to check are the throttle cable, is it adjusted so the arm stops 1mm from the wide open stop on the throttle body when a helper mashes the pedal to the floor?
When it's idling use gloves or insulated pliers and pull one spark plug wire from the cap, does the idle speed drop?, put it back and move on to the next one, same thing with all 4. If one doesn't make any difference it's time to find out why that cylinder is dead.
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Rust NEVER sleeps and stock never goes out of style.
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cfroderman
Samba Member
Joined: November 23, 2021
Posts: 29
Location: Avon, IN
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| Posted: Sun May 15, 2022 1:35 pm Post subject: Re: Official Fuel injection questions thread |
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I misunderstood on the fuel pressure switch. I just put a vacuum on the entire system and there was no vacuum pressure drop. I was just looking for a vacuum leak somewhere. So you are saying, with the engine running at idle, put a vacuum on the fuel pressure switch and measure the fuel pressure?
I double checked the throttle cable and it stops at the correct spot.
I will give the cylinder test a try as well. |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51123
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Sun May 15, 2022 3:00 pm Post subject: Re: Official Fuel injection questions thread |
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The fuel pressure regulator (FPR) located in the return line where it passes through the tin ahead of cylinder #1 has a small vacuum line coming from it, it should be connected to the throttle body (TB) or plenum (consult the vacuum diagram for your model). When vacuum is applied to that line the fuel pressure should drop, or when idling pulling the line off the TB should make the pressure rise.
_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
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cfroderman
Samba Member
Joined: November 23, 2021
Posts: 29
Location: Avon, IN
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| Posted: Mon May 16, 2022 6:05 pm Post subject: Re: Official Fuel injection questions thread |
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| busdaddy wrote: |
| The fuel pressure regulator (FPR) located in the return line where it passes through the tin ahead of cylinder #1 has a small vacuum line coming from it, it should be connected to the throttle body (TB) or plenum (consult the vacuum diagram for your model). When vacuum is applied to that line the fuel pressure should drop, or when idling pulling the line off the TB should make the pressure rise. |
Tested fuel pressure and vacuum tonight. While idling with all vacuum hoses connected everywhere, fuel pressure was 37 psi. I pulled the hose from the FPR and the pressure increased to 39 psi. I then put a vacuum on the FPR hose of ~ 23 in Hg and the fuel pressure dropped to ~ 26 psi.
I've tested the advance with a timing light with and without vacuum and all appears to be fine on that end. The engine starts easily and idles without missing any cylinders. I'm at a loss. |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51123
Location: Surrey B.C. Canada, but thinking of Ukraine
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Maltboy!
Samba Member
Joined: June 17, 2006
Posts: 137
Location: Santa Fe, Texas
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| Posted: Tue May 17, 2022 7:03 am Post subject: Re: Official Fuel injection questions thread |
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| cfroderman wrote: |
77 VW Super Beetle Convertible - Engine Fire restoration -
Symptom - Slow build up of speed while driving - Poor power in all gears. It seems like the speed will gradually build up even with accelerator floored. Starts with no problems.
Any other items I should look at? |
Just curious, What do you mean by slow? How long from 0-60 MPH?
_________________
76 Super Beetle convertible, Ford Chrome Yellow - body-off restoration, 100% of work done by me
59 Beetle convertible, future project - 25,000 actual miles, original interior |
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cfroderman
Samba Member
Joined: November 23, 2021
Posts: 29
Location: Avon, IN
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| Posted: Tue May 17, 2022 7:29 am Post subject: Re: Official Fuel injection questions thread |
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Just tested the dead cylinders - 1 & 4 cylinders did not effect rpms. 2 & 3 dropped the RPM's down considerably. So that appears to be the culprit. I'm definitely getting spark at the distributor when I pulled the wires. Next suggested steps? Check spark at the spark plug?
I pulled all the injectors when I had it apart early on and cleaned them with carb cleaner under pressure while activating them, so I know the injectors work and are not clogged. If I recall, injectors are "always on" and aren't timed are they? Crossed wires?
Maltboy! - Minutes to get to 60. Accelerator flat to the floor, I would take a minute to get to 60 on a flat surface. Based on the above test, I'm only using 1/2 the cylinders..  |
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VW_Jimbo 
Samba Member
Joined: May 22, 2016
Posts: 9954
Location: Huntington Beach, CA
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| Posted: Tue May 17, 2022 8:26 am Post subject: Re: Official Fuel injection questions thread |
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You stated that the distributor tested out good. Hmmm.
Does the vacuum can pull the points plate when vacuum is applied? Should move smooth and easy when it does move.
Also the weights down under the points plate. What do they look like and can you hear them open and close when you spin the distributor in your hands?
Shit! For that matter. Is the pull arm from the diaphragm connected to the points plate?
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Jimbo
There is never enough time to do it right the first time, but all the time necessary the second time!
| TDCTDI wrote: |
| Basically, a whole bunch of fuckery to achieve a look. |
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cfroderman
Samba Member
Joined: November 23, 2021
Posts: 29
Location: Avon, IN
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| Posted: Tue May 17, 2022 8:34 am Post subject: Re: Official Fuel injection questions thread |
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| VW_Jimbo wrote: |
You stated that the distributor tested out good. Hmmm.
Does the vacuum can pull the points plate when vacuum is applied? Should move smooth and easy when it does move.
Also the weights down under the points plate. What do they look like and can you hear them open and close when you spin the distributor in your hands?
Shit! For that matter. Is the pull arm from the diaphragm connected to the points plate? |
The advance and retard all tested OK with a timing light and RPM for Bosch 0231 176 044 distributor. See posts above that the vacuum caused the breaker plate to move at ~ 5 in Hg on both the advance and retard side. I tested the centrifugal advance as well without vacuum. It all tested OK.
I'm more worried that only 2 cylinders appear to be firing at idle. I'm getting spark at the distributor cap when I pulled the wires individually. |
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Maltboy!
Samba Member
Joined: June 17, 2006
Posts: 137
Location: Santa Fe, Texas
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| Posted: Tue May 17, 2022 8:46 am Post subject: Re: Official Fuel injection questions thread |
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| cfroderman wrote: |
The advance and retard all tested OK with a timing light and RPM for Bosch 0231 176 044 distributor. See posts above that the vacuum caused the breaker plate to move at ~ 5 in Hg on both the advance and retard side. I tested the centrifugal advance as well without vacuum. It all tested OK.
I'm more worried that only 2 cylinders appear to be firing at idle. I'm getting spark at the distributor cap when I pulled the wires individually. |
Have you checked the resistor pack for broken wires?
_________________
76 Super Beetle convertible, Ford Chrome Yellow - body-off restoration, 100% of work done by me
59 Beetle convertible, future project - 25,000 actual miles, original interior |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51123
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Tue May 17, 2022 8:58 am Post subject: Re: Official Fuel injection questions thread |
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| Maltboy! wrote: |
| cfroderman wrote: |
The advance and retard all tested OK with a timing light and RPM for Bosch 0231 176 044 distributor. See posts above that the vacuum caused the breaker plate to move at ~ 5 in Hg on both the advance and retard side. I tested the centrifugal advance as well without vacuum. It all tested OK.
I'm more worried that only 2 cylinders appear to be firing at idle. I'm getting spark at the distributor cap when I pulled the wires individually. |
Have you checked the resistor pack for broken wires? |
That's where I'd go next, if the injectors bench tested OK then it's got to be electrical.
If the harness is bendy enough try swapping the injector plugs and see if the dead cylinders move with the plugs. It's batch fire so, mixing them doesn't matter.
_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
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mukluk
Samba Member
Joined: October 18, 2012
Posts: 7023
Location: Clyde, TX
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| Posted: Tue May 17, 2022 9:00 am Post subject: Re: Official Fuel injection questions thread |
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Have you double checked that you didn't accidentally swap #1 and 4 plug wires at the distributor? It happens. Checking for spark at the plugs would be a good step.
Have you verified the injectors on #1 and 4 are firing? You should be able to hear them clicking with a mechanic's stethoscope or similar tool while the engine is running. If they're not firing, check to see if they're getting power and that the ground/control wires running to the ECM aren't damaged.
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Maltboy!
Samba Member
Joined: June 17, 2006
Posts: 137
Location: Santa Fe, Texas
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| Posted: Tue May 17, 2022 9:01 am Post subject: Re: Official Fuel injection questions thread |
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| busdaddy wrote: |
| Maltboy! wrote: |
Have you checked the resistor pack for broken wires? |
That's where I'd go next, if the injectors bench tested OK then it's got to be electrical.
If the harness is bendy enough try swapping the injector plugs and see if the dead cylinders move with the plugs. It's batch fire so, mixing them doesn't matter. |
I had a broken wire where the harness connects to the resistor. I was able to track it down with a NOID tester.
_________________
76 Super Beetle convertible, Ford Chrome Yellow - body-off restoration, 100% of work done by me
59 Beetle convertible, future project - 25,000 actual miles, original interior |
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cfroderman
Samba Member
Joined: November 23, 2021
Posts: 29
Location: Avon, IN
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| Posted: Tue May 17, 2022 9:44 am Post subject: Re: Official Fuel injection questions thread |
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| Maltboy! wrote: |
| busdaddy wrote: |
| Maltboy! wrote: |
Have you checked the resistor pack for broken wires? |
That's where I'd go next, if the injectors bench tested OK then it's got to be electrical.
If the harness is bendy enough try swapping the injector plugs and see if the dead cylinders move with the plugs. It's batch fire so, mixing them doesn't matter. |
I had a broken wire where the harness connects to the resistor. I was able to track it down with a NOID tester. |
All great suggestions. I will try them this afternoon. Major problem is that I don't see a resistance block connection plug in the engine compartment. The wiring harness comes directly from the control box. I do have an upgraded alternator. Would that eliminate the resistance block? I thought I read somewhere that it did. |
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cfroderman
Samba Member
Joined: November 23, 2021
Posts: 29
Location: Avon, IN
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| Posted: Tue May 17, 2022 10:26 am Post subject: Re: Official Fuel injection questions thread |
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| Update - swapping the injector wires caused the dead cylinders to follow. Testing the injector wires with the ignition on showed 12 volts. The fact that the dead cylinders followed the wire switch would indicate an electrical problem. I’m not sure where to go here since I don’t have a resistance block that I can find. I appreciate all the help and suggestions. |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51123
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Tue May 17, 2022 10:36 am Post subject: Re: Official Fuel injection questions thread |
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Resistors are located on the inside of the RR fenderwell, inboard of the tail light, hiding under the tar board.
_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
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cfroderman
Samba Member
Joined: November 23, 2021
Posts: 29
Location: Avon, IN
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| Posted: Tue May 17, 2022 12:08 pm Post subject: Re: Official Fuel injection questions thread |
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| Resistor block was found and one wire was broken. Great call. Repaired it and now have 3 out of 4 cylinders working as indicated by pulling spark plug wires and noting idle speed. Any ideas/links on how to test the block to make sure all resistors are working correctly? |
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