Forgot to sent this to the net too.
> Begin forwarded message:
>
> From: John Wright
> Subject: Re: [GMCMH-EFI] Gerald Downing EFI
> Date: October 18, 2017 at 3:55:58 PM EDT
> To: gmcmh-efi
>
> I have a similar system in my coach. Rule number ONE, if it idles and runs up to 25 or 30 MPH or chocks on acceleration then check the fuel pressure. Should be 40 psig to 55 psig. Anything lower than 40 psig and it will not run well! Mine typically is about 52 psig.
>
> The first picture is the fuel pressure regulator and my remote coil installation.
>
> http://www.gmcmhphotos.com/photos/general-pictures/p63437-img-18261.html
>
> This is the photo album on the system that I have, Notice how similar it is except for the throttle body.
>
> http://www.gmcmhphotos.com/photos/g6148-accel-gen-6-mpfi.html
>
> And my fuel system.
>
> http://www.gmcmhphotos.com/photos/g7092-accel-gen-6-pictures.html
>
> I would also need to know what color injectors that are installed in the manifold. I can then tell you what they are and I have the part numbers for most of the efi parts on the manifold including the regulator.
>
> This is the fuel pump that can be used.
>
> https://www.ebay.com/itm/New-Electric-Fuel-Pump-Gas-Mercedes-190-580254942-Mercedes-Benz-300E-190E-450SL-/271279136219?hash=item3f297f1ddb:g:ggwAAOSwGIBZsz6K&vxp=mtr
> or
> http://tinyurl.com/y7j2jaca
>
> The O2 Sensor that I use is the following and if yours is a 3 wire sensor then this will work with the ECU. Bosch # 13077
>
> https://www.napaonline.com/en/p/BSA13077?interchange=1
>
> Heat the bung up with a torch and stick the longest wrench you can get on and it should come out.
>
> If you have any other questions, please ask!
>
> JR Wright
> GMC Great Laker MHC
> GMC Eastern States Charter Member
> GMCGL Tech Editor
> GMCMI
> 78 GMC Buskirk 30’ Stretch
> 1975 GMC Avion (Under Reconstruction)
> Michigan
>
>
>
>
>>
>> Ken, back to the basics. Check for full battery voltage, then running system voltage. Ok? Not ok? Fix that. Move to connectors and plugs and harnesses. Ok? Not OK? fix that. When all electrics have been verified to be ok, start with fuel pressure under load. Helps if you have the specs, but if you are under 35psi, replace the pump. Clean all filters air and fuel. Check fuel supply ( bad gas) jwiwd.
>> Jim Hupy
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Spitting and backfiring is a lean mixture and probably caused by one of the injectors OR as in my case on a 4 cylinder which I have replaced all the spark plugs, wires, cleaned the injector, IT WAS A FLAKY connection right at the injector. Pull the injectors, look at the spray pattern FIRST, then clean and look again. Look at the electrical connection on all the injectors. Clean them and measure the resistance of each injector. Without being able to look at the mixture condition when the fault occurs, you are blind. I am assuming you have checked the fuel pressure when the fault occurs?
>>
>>> Gerald Downing, from Dothan, AL, is visiting to see if we can get his '78 403's EFI working better. Until about February, he says the coach ran great, then began to miss erratically. He's had several people try to work on it, including Alex Ferrara, and an 84 yo former Olds mechanic from the '70's. No one has made any progress.
>>>
>>> The engine idles roughly, with a erratic miss -- NOT consistent as if coming from one cylinder. All of the spark plugs and wires, the ignition coil, cap, rotor, and the 7-pin module have been replaced. About the first thing I did after he opened the engine hatch was remove the distributor cap and shake the rotor. It moved side-to-side maybe 0.010"-0.015" -- too much, IMHO. I happened to have one, with no lateral play, so I installed it. If anything, the engine ran even worse!
>>>
>>> I then reset the timing as well as I could, by vacuum reading (his guage responds VERY slowly). Since I know NOTHING about the electronics of this system, I couldn't disable any ECU advance. Besides, there seems to be no timing pointer on the engine. Still no improvement. The engine stutters, stumbles, sometimes spits & backfires on low speed acceleration. When not under load, it runs perfectly -- smooth, quiet, with no indication of any problem. During acceleration, it begins to stutter again. At speed (50+ mph), it smooths out with only an occasional hiccup -- until a significant hill, then it stutters.
>>>
>>> We have found nothing to tell us where the EFI came from. It has a 2-barrel throttle body by Bendix and what appears to me to be a GM ECU, though I don't have a number from it. The photo below is not very good, but I'm hoping someone will recognize some part of the system.
>>>
>>> The aluminum fuel rails are connected at the front with a braided SS line. At the rear of each rail is another SS line with the two teed together; I PRESUME that's the return to the tanks. At near the center of the right rail is black cylinder, below the rail, with another SS line entering one end of the cylinder. The other end of the cylinder connects to a vacuum hose which, in turn, goes to the front of the throttle body; that cylinder is, I PRESUME, the manifold vacuum sensitive fuel pressure regulator; its location sort of baffles me though.
>>>
>>> I'm about at the end of my rope with the thing with NO documentation to help me and no knowledge of port injection, so any help will be appreciated.
>>>
>>> One thing we haven't tried, but plan to this morning, is replacement of the O2 sensor. I'll report the results of that.
>>>
>>> Oh yeah, one other thing I did: the round device just aft of the air inlet snorkel is the IAC, I finally figured out. Unlike our TBI systems, the IAC admits air through that little filter rather than using system air from the throttle body. That filter was VERY dirty, so I removed it and blew if out with compressed air. The pintle was completely black with carbon, which washed off with solvent. When first started and revved at idle, that seemed to correct the problem -- when driven, there was no improvement.
>>>
>>> Without help from Y'All, we have no idea what to do next except replace the system entirely.
>>>
>>> Here's a shot of the system:
>>>
>>> https://drive.google.com/open?id=0B3XquSIYjDlecWFpbExxS1ZhbFk
>>>
>>> Ken H.
>>> Americus, GA
>>> '76 X-Birchaven w/Cad500/Howell EFI & EBL,
>>> Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
>>> www.gmcwipersetc.com
>>> --
>>> You received this message because you are subscribed to the Google Groups "GMCMH EFI" group.
>>> To unsubscribe from this group and stop receiving emails from it, send an email to gmcmh-efi+unsubscribe
>>> To post to this group, send email to gmcmh-efi
>>> Visit this group at https://groups.google.com/group/gmcmh-efi.
>>> For more options, visit https://groups.google.com/d/optout.
>>
>>
>> --
>> You received this message because you are subscribed to the Google Groups "GMCMH EFI" group.
>> To unsubscribe from this group and stop receiving emails from it, send an email to gmcmh-efi+unsubscribe
>> To post to this group, send email to gmcmh-efi
>> Visit this group at https://groups.google.com/group/gmcmh-efi.
>> For more options, visit https://groups.google.com/d/optout.
>>
>> --
>> You received this message because you are subscribed to the Google Groups "GMCMH EFI" group.
>> To unsubscribe from this group and stop receiving emails from it, send an email to gmcmh-efi+unsubscribe
>> To post to this group, send email to gmcmh-efi
>> Visit this group at https://groups.google.com/group/gmcmh-efi.
>> For more options, visit https://groups.google.com/d/optout.
>
> Begin forwarded message:
>
> From: John Wright
> Subject: Re: [GMCMH-EFI] Gerald Downing EFI
> Date: October 18, 2017 at 3:55:58 PM EDT
> To: gmcmh-efi
>
> I have a similar system in my coach. Rule number ONE, if it idles and runs up to 25 or 30 MPH or chocks on acceleration then check the fuel pressure. Should be 40 psig to 55 psig. Anything lower than 40 psig and it will not run well! Mine typically is about 52 psig.
>
> The first picture is the fuel pressure regulator and my remote coil installation.
>
> http://www.gmcmhphotos.com/photos/general-pictures/p63437-img-18261.html
>
> This is the photo album on the system that I have, Notice how similar it is except for the throttle body.
>
> http://www.gmcmhphotos.com/photos/g6148-accel-gen-6-mpfi.html
>
> And my fuel system.
>
> http://www.gmcmhphotos.com/photos/g7092-accel-gen-6-pictures.html
>
> I would also need to know what color injectors that are installed in the manifold. I can then tell you what they are and I have the part numbers for most of the efi parts on the manifold including the regulator.
>
> This is the fuel pump that can be used.
>
> https://www.ebay.com/itm/New-Electric-Fuel-Pump-Gas-Mercedes-190-580254942-Mercedes-Benz-300E-190E-450SL-/271279136219?hash=item3f297f1ddb:g:ggwAAOSwGIBZsz6K&vxp=mtr
> or
> http://tinyurl.com/y7j2jaca
>
> The O2 Sensor that I use is the following and if yours is a 3 wire sensor then this will work with the ECU. Bosch # 13077
>
> https://www.napaonline.com/en/p/BSA13077?interchange=1
>
> Heat the bung up with a torch and stick the longest wrench you can get on and it should come out.
>
> If you have any other questions, please ask!
>
> JR Wright
> GMC Great Laker MHC
> GMC Eastern States Charter Member
> GMCGL Tech Editor
> GMCMI
> 78 GMC Buskirk 30’ Stretch
> 1975 GMC Avion (Under Reconstruction)
> Michigan
>
>
>
>
>>
>> Ken, back to the basics. Check for full battery voltage, then running system voltage. Ok? Not ok? Fix that. Move to connectors and plugs and harnesses. Ok? Not OK? fix that. When all electrics have been verified to be ok, start with fuel pressure under load. Helps if you have the specs, but if you are under 35psi, replace the pump. Clean all filters air and fuel. Check fuel supply ( bad gas) jwiwd.
>> Jim Hupy
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Spitting and backfiring is a lean mixture and probably caused by one of the injectors OR as in my case on a 4 cylinder which I have replaced all the spark plugs, wires, cleaned the injector, IT WAS A FLAKY connection right at the injector. Pull the injectors, look at the spray pattern FIRST, then clean and look again. Look at the electrical connection on all the injectors. Clean them and measure the resistance of each injector. Without being able to look at the mixture condition when the fault occurs, you are blind. I am assuming you have checked the fuel pressure when the fault occurs?
>>
>>> Gerald Downing, from Dothan, AL, is visiting to see if we can get his '78 403's EFI working better. Until about February, he says the coach ran great, then began to miss erratically. He's had several people try to work on it, including Alex Ferrara, and an 84 yo former Olds mechanic from the '70's. No one has made any progress.
>>>
>>> The engine idles roughly, with a erratic miss -- NOT consistent as if coming from one cylinder. All of the spark plugs and wires, the ignition coil, cap, rotor, and the 7-pin module have been replaced. About the first thing I did after he opened the engine hatch was remove the distributor cap and shake the rotor. It moved side-to-side maybe 0.010"-0.015" -- too much, IMHO. I happened to have one, with no lateral play, so I installed it. If anything, the engine ran even worse!
>>>
>>> I then reset the timing as well as I could, by vacuum reading (his guage responds VERY slowly). Since I know NOTHING about the electronics of this system, I couldn't disable any ECU advance. Besides, there seems to be no timing pointer on the engine. Still no improvement. The engine stutters, stumbles, sometimes spits & backfires on low speed acceleration. When not under load, it runs perfectly -- smooth, quiet, with no indication of any problem. During acceleration, it begins to stutter again. At speed (50+ mph), it smooths out with only an occasional hiccup -- until a significant hill, then it stutters.
>>>
>>> We have found nothing to tell us where the EFI came from. It has a 2-barrel throttle body by Bendix and what appears to me to be a GM ECU, though I don't have a number from it. The photo below is not very good, but I'm hoping someone will recognize some part of the system.
>>>
>>> The aluminum fuel rails are connected at the front with a braided SS line. At the rear of each rail is another SS line with the two teed together; I PRESUME that's the return to the tanks. At near the center of the right rail is black cylinder, below the rail, with another SS line entering one end of the cylinder. The other end of the cylinder connects to a vacuum hose which, in turn, goes to the front of the throttle body; that cylinder is, I PRESUME, the manifold vacuum sensitive fuel pressure regulator; its location sort of baffles me though.
>>>
>>> I'm about at the end of my rope with the thing with NO documentation to help me and no knowledge of port injection, so any help will be appreciated.
>>>
>>> One thing we haven't tried, but plan to this morning, is replacement of the O2 sensor. I'll report the results of that.
>>>
>>> Oh yeah, one other thing I did: the round device just aft of the air inlet snorkel is the IAC, I finally figured out. Unlike our TBI systems, the IAC admits air through that little filter rather than using system air from the throttle body. That filter was VERY dirty, so I removed it and blew if out with compressed air. The pintle was completely black with carbon, which washed off with solvent. When first started and revved at idle, that seemed to correct the problem -- when driven, there was no improvement.
>>>
>>> Without help from Y'All, we have no idea what to do next except replace the system entirely.
>>>
>>> Here's a shot of the system:
>>>
>>> https://drive.google.com/open?id=0B3XquSIYjDlecWFpbExxS1ZhbFk
>>>
>>> Ken H.
>>> Americus, GA
>>> '76 X-Birchaven w/Cad500/Howell EFI & EBL,
>>> Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
>>> www.gmcwipersetc.com
>>> --
>>> You received this message because you are subscribed to the Google Groups "GMCMH EFI" group.
>>> To unsubscribe from this group and stop receiving emails from it, send an email to gmcmh-efi+unsubscribe
>>> To post to this group, send email to gmcmh-efi
>>> Visit this group at https://groups.google.com/group/gmcmh-efi.
>>> For more options, visit https://groups.google.com/d/optout.
>>
>>
>> --
>> You received this message because you are subscribed to the Google Groups "GMCMH EFI" group.
>> To unsubscribe from this group and stop receiving emails from it, send an email to gmcmh-efi+unsubscribe
>> To post to this group, send email to gmcmh-efi
>> Visit this group at https://groups.google.com/group/gmcmh-efi.
>> For more options, visit https://groups.google.com/d/optout.
>>
>> --
>> You received this message because you are subscribed to the Google Groups "GMCMH EFI" group.
>> To unsubscribe from this group and stop receiving emails from it, send an email to gmcmh-efi+unsubscribe
>> To post to this group, send email to gmcmh-efi
>> Visit this group at https://groups.google.com/group/gmcmh-efi.
>> For more options, visit https://groups.google.com/d/optout.
>
