Fuel Injection problem CIS

jason442 · 09-08-2008, 09:49 AM

Just finished a 2.7 rebuild and am starting for the first time. Last night I was able to get it to run with starting fluid but only for about 10 seconds. If I have a friend push that metal thing? inside the airbox on the right side top area it runs (made it about 3 minutes) at 1700 to 2100rpms. Not sure what to try next or how to tell if I have fuel pressure. Will it run without the cover and filter on? When we put the cover on it wont start at all.
Thanks in advance.

Jason

T77911S · 09-08-2008, 10:38 AM

when you say "push the meatal thing" i assume you are talking about the "plate" and that you are pushing it up.
if so, that would indicate the mixture is lean, due to either air leak or the fact that the new motor reqires a different setting of the mixture. there is a small hole in the top of the AFM between the fuel distributor(FD) and the rubber boot. use a long 3mm allen and turn the screw CW to richen in 1/8 th increments.

boyt911sc · boyt911sc's Garage

Jason,

Your starting problem/s could be some what similar to one of Euro911SC's threads. So not to be redundant, I suggest you follow that with interest.

Tony

don gilbert · don gilbert's Garage

check for return fuel line restriction

don gilbert · don gilbert's Garage

but you should first confirm correct system pressures

jason442 · 09-08-2008, 08:10 PM

(1975 911s) I installed a pop off valve previously and upon closer inspection it looked like it didnt have a good seal. After work tonight I sealed it well with silicone and went home for a few hours. I talked a friend into helping me with the project. He didn't want to wait the full 20 minutes for proper engine breakin if it started so we crushed 3 beercans at different sizes to put under the air sensor plate. It started fine but the can he needed was between sizes and he couldn't reach the empties. I explained to him that once it started we couldn't stop till the recommended 20 minutes was up and we made it the full 20. When it dipped below 2000rpms (only a couple times) it tended to backfire.
As long as the air sensor plate is held up about 1/4 inch it runs fine at about 2100rpm. I can push the footfeet (hillbilly term?) and get to higher RPM's without difficulty. I tried to richen the fuel mixture with a 3mm allen but it wouldn't turn. I tried to turn the screw fairly hard and it wouldn't budge. I was afraid I'd break something being a novice and all.
A friend on my hockey team is a honda mechanic and said he'd help me tomorrow night. Any special tools I should tell him to bring? Any advice? Please don't tell me to keep the empties closer to the car.

Thanks,

Jason

T77911S · 09-09-2008, 03:52 AM

check pressures, if you dont have gauges yet, check the screen on the WUR, if it is clogged it will make it run lean.
did the CIS sit for a long time not being used?

javadog · 09-09-2008, 04:13 AM

Is there any reason why you don't want to just haul the car to a good shop that knows a 911 well, and have them sort it out? I don't want to offend you but you don't seem to have a good understanding of the CIS system and I'm going to guess that you don't have the tools you need to properly diagnose the problem. Sometimes it's better to just have someone else do the work. The last thing you want to do is screw up a fresh rebuild.

Good luck,
JR

jason442 · 09-09-2008, 04:26 AM

I'll check the filter tonight. If I take it to a shop I'll loose the bet with my boss that I coudn't fix it by next monday. The CIS has been sitting on a shelf for about 8 months. I'm allready searching for a mechanic who knows my car and plan to swallow my pride and take it in next week if I cant get it going. Should that screw that changes the fuel mixture be that hard to turn?

Jason

T77911S · 09-09-2008, 04:37 AM

no it is not hard to turn. thats why i asked about the condition of the CIS. if it has been sitting for a long time it could get gummed up. with the key off, the plate should lift and fall VERY easily, along with the plunger in the FD.
did you try turning the screw CCW?
check the screen on the WUR. they have been known to get clogged and raise the control pressure(CP) and lean it out.

if you want to learn about CIS, now is the time, its really not that hard. you need a pressure gauge. here is a good place to start. http://members.rennlist.com/jimwms/CIS/CIShome.html