# CIS pressure or bad injector?



## boisebimmer (Oct 3, 2012)

Backstory:
Well, I've been working on fixing a car that had been sitting for a few years. It wouldn't start but was cranking over. After new Cap and rotor, and plugs I was getting spart. But I wasn't getting any fuel. After testing it was discovered that the pumps were both bad, so I replaced them. I pulled the injectors and ran carb cleaner through and they all have consistant spray patterns. I've sprayed out the fuel lines as well, they seem good.

Now that we have both pumps in we now are at the test the CIS stage. We put in the jump wire, and pull up on the air plate and we are getting fuel, but not through the injectors. We pull the injectors and mesure the fuel and we are getting 50cc of fuel per 30/s. This seems to be about right per the Bently manual for 11.4 volts. 

Question:
Now I'm at a loss, I don't know weather I have bad injectors or if I'm having an issue with the pressure from the CIS or fuel pumps. 

I'm not sure of where to go from here. Injectors are expensive so I don't want to just throw money at them hoping thats it. Is there ay way to nail down if the issue is pressure or injectors?


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## rabbitnothopper (Oct 19, 2009)

yes...fuel pressure test

if you are getting 65-72psi at the fuel outlet on the top of the FD
then you are within the ballpark and the pump works as indicated

i think you should be getting more fuel out of the injectors than that

try removing the injectors and spraying 1 entire bottle of B12 chemtool through it
1 bottle per injector = $12

spray until the pattern is a nice mist


there are probally a lot of things you need to do really

fresh fuel
look INSIDE of the tank -- rust?

check the CPR pressure cold/warm
check system pressure
check injector flow rate and spray pattern
test the cold start valve

etc

it is also possible you are flooding the engine
this causes starting to be very difficult
hold the pedal to the floor while you crank it for 5-10 seconds (not more than 15 seconds)
this allows the flooded engine to evaporate sufficiently and clear the cylidners of gas


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## boisebimmer (Oct 3, 2012)

rabbitnothopper said:


> yes...fuel pressure test
> 
> if you are getting 65-72psi at the fuel outlet on the top of the FD
> then you are within the ballpark and the pump works as indicated
> ...



We are testing with jumper wire, the injectors are pulled from the head and there is no timing belt. 

Both fuel pumps were just replaced with brand new OEM ones, so I couldn't foresee those being the issue.

We are not worried about the quality of the fuel since we are at this point just trying to get injectors to spray, even a little. 

Last night we cleaned the injectors using a bosch cleaning cool, they had OK, spray patterns. I also left them to soak in seafoam overnight. 

We are only maybe a little short of fuel per the bently. So I'm not worried about the amount of fuel we are getting, I'm thinking its gotta be either we have not enough pressure or the injectors are just bad, although they are spraying a fine mist of carb cleaner. 

I believe the tank is plastic, so it can't rust, also when I replaced the intank pump there was no rust in there.


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## boisebimmer (Oct 3, 2012)

Fixing issue by going to MS.


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## bugsinmyteeth (Feb 8, 2006)

There is often an inline screen where the fuel inlet meets the fuel distributor. It's inside the banjo bolt. Than can get corrosion which closes it off if the car sits a long time. The screen can be removed and just rely on the filter to keep things clean.


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