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SGKent 
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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 Posted: Thu Dec 13, 2018 4:37 pm Post subject: Re: 77 FI intake backfire on start |
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| timvw7476 wrote: |
This thread seems to have changed into a fuel delivery when at temp issue.
Tired fuel pump/bad double relay are the usual suspects for that fail. |
so what is igniting the fuel in the intake area? Anyone think that thru? (I have)
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OG Velvet
Samba Family Man
Joined: February 24, 2003
Posts: 2168
Location: Portland, OR
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| Posted: Fri Dec 14, 2018 12:55 pm Post subject: Re: 77 FI intake backfire on start |
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Valves adjusted
Double relay is only a year old
Maybe fuel pump?
Yes there are two separate issues in this thread.
Original issue- Occasional backfire through intake, blowing off hoses. Mainly the breather hose
Issue that developed- Engine shutting off when warm. Mind you, it's not bucking or hesitating or sputtering. It's shutting off.
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'77 Westy
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Fri Dec 14, 2018 1:12 pm Post subject: Re: 77 FI intake backfire on start |
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| OG Velvet wrote: |
Valves adjusted
Double relay is only a year old
Maybe fuel pump?
Yes there are two separate issues in this thread.
Original issue- Occasional backfire through intake, blowing off hoses. Mainly the breather hose
Issue that developed- Engine shutting off when warm. Mind you, it's not bucking or hesitating or sputtering. It's shutting off. |
it is either loss of spark or loss of fuel. If spark is lost then the ECU won't open the injectors either.
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OG Velvet
Samba Family Man
Joined: February 24, 2003
Posts: 2168
Location: Portland, OR
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| Posted: Fri Jan 11, 2019 5:59 pm Post subject: Re: 77 FI intake backfire on start |
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Replaced the AFM. I just drove it around for the last half hour or so (sticking close to home) and no problems so far. I got it good and warm and the shutting off issue did not return. I'm going to try a bit further from home tomorrow. I still plan to have all of my injectors (especially the CSV) serviced next week just for shits and giggles. I will be nice to get back to work on the other issues this bus has.. this issue was a long distraction... cross your fingers...
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dstimm
Samba Member
Joined: June 29, 2018
Posts: 153
Location: Encinitas, CA
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| Posted: Fri Jan 11, 2019 9:37 pm Post subject: Re: 77 FI intake backfire on start |
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| OG Velvet wrote: |
| Replaced the AFM. I just drove it around for the last half hour or so (sticking close to home) and no problems so far. I got it good and warm and the shutting off issue did not return. I'm going to try a bit further from home tomorrow. I still plan to have all of my injectors (especially the CSV) serviced next week just for shits and giggles. I will be nice to get back to work on the other issues this bus has.. this issue was a long distraction... cross your fingers... |
Wow, wish there was an easier way to test an AFM. I just had my injectors done by Mr Injector (he was fast, affordable, and did an amazing job). Send your cold start injector at the same time btw.
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OG Velvet
Samba Family Man
Joined: February 24, 2003
Posts: 2168
Location: Portland, OR
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| Posted: Wed Jan 16, 2019 6:43 pm Post subject: Re: 77 FI intake backfire on start |
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**Update** (because I really hate it when problem solving threads don't show the solution...)
Replacing the AFM seems to have fixed both issues. I've been driving the bus daily for the last few days and it runs like a dream. (still gonna knock on wood)
Thanks again for all of the help and replies.
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Wed Jan 16, 2019 6:50 pm Post subject: Re: 77 FI intake backfire on start |
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| OG Velvet wrote: |
**Update** (because I really hate it when problem solving threads don't show the solution...)
Replacing the AFM seems to have fixed both issues. I've been driving the bus daily for the last few days and it runs like a dream. (still gonna knock on wood)
Thanks again for all of the help and replies. |
if it was the AFM then the backfiring was loss of fuel. The lean mixture moves the fuel molecules farther apart. They burn slower and the mixture is still burning when new fuel and air goes into the cylinder causing a backfire.
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OG Velvet
Samba Family Man
Joined: February 24, 2003
Posts: 2168
Location: Portland, OR
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| Posted: Wed Jan 16, 2019 6:54 pm Post subject: Re: 77 FI intake backfire on start |
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| SGKent wrote: |
| OG Velvet wrote: |
**Update** (because I really hate it when problem solving threads don't show the solution...)
Replacing the AFM seems to have fixed both issues. I've been driving the bus daily for the last few days and it runs like a dream. (still gonna knock on wood)
Thanks again for all of the help and replies. |
if it was the AFM then the backfiring was loss of fuel. The lean mixture moves the fuel molecules farther apart. They burn slower and the mixture is still burning when new fuel and air goes into the cylinder causing a backfire. |
Well to be honest, I'm going to give it a couple weeks before I call the intake backfire fixed. It was very random. I didn't even touch the screw on the AFM when I installed it out of the box. Is there a default I should set it to?
Like I said above, I will get all injectors serviced soon along with the CSV just in case.
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LostnaWesty
Samba Member
Joined: April 10, 2014
Posts: 77
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| Posted: Fri Dec 04, 2020 5:33 pm Post subject: Re: 77 FI intake backfire on start |
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| OG Velvet wrote: |
| SGKent wrote: |
| OG Velvet wrote: |
**Update** (because I really hate it when problem solving threads don't show the solution...)
Replacing the AFM seems to have fixed both issues. I've been driving the bus daily for the last few days and it runs like a dream. (still gonna knock on wood)
Thanks again for all of the help and replies. |
if it was the AFM then the backfiring was loss of fuel. The lean mixture moves the fuel molecules farther apart. They burn slower and the mixture is still burning when new fuel and air goes into the cylinder causing a backfire. |
Well to be honest, I'm going to give it a couple weeks before I call the intake backfire fixed. It was very random. I didn't even touch the screw on the AFM when I installed it out of the box. Is there a default I should set it to?
Like I said above, I will get all injectors serviced soon along with the CSV just in case. |
still goin strong? |
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