Fuel Pressue test
06-07-2009, 02:16 PM
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Fuel Pressue test
Where do I test my fuel pressure? I rebuilt my fuel distributor, again, and it's still not putting out enough fuel to the injectors.
Where and how do I test the fuel pressure going into it?
Also, would having the air/fuel screw off not allow enough fuel to the fuel distributor? The car only runs when you first start it, getting fuel from the cold start, or if I pour fuel into the intake...
I could really use some help, thanks...
Where and how do I test the fuel pressure going into it?
Also, would having the air/fuel screw off not allow enough fuel to the fuel distributor? The car only runs when you first start it, getting fuel from the cold start, or if I pour fuel into the intake...
I could really use some help, thanks...
06-07-2009, 02:26 PM
#3
Drifting
There is a test point at front of rhs fuel rail which just unscrews (make sure to counterhold, and get ready to catch the ball bearing sealer if it falls out the cap), but you will require adapter to attach pressure gauge.
06-07-2009, 03:34 PM
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BB79,
Reading your post and reference to fuel distributor, I'm assuming your talking about a 79 CIS model. If so, there are no fuel rails and you can't tap that point for pressure.
The CIS system has two key pressures, system pressure and control pressure. You need a pressure test set up that will allow you to make these tests and they will tell you alot about what problems you may have. With out that ability, you're not going to get very far. JC Whitney, Harbor Freight and others have a fuel pressure test set up with adaptors for CIS systems.
Reading your post and reference to fuel distributor, I'm assuming your talking about a 79 CIS model. If so, there are no fuel rails and you can't tap that point for pressure.
The CIS system has two key pressures, system pressure and control pressure. You need a pressure test set up that will allow you to make these tests and they will tell you alot about what problems you may have. With out that ability, you're not going to get very far. JC Whitney, Harbor Freight and others have a fuel pressure test set up with adaptors for CIS systems.
06-07-2009, 03:51 PM
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http://www.harborfreight.com/cpi/cta...emnumber=97706
This one will work. You can take a look at the manual on the HF site. Do you have the workshop manual? A CIS manual is really useful also.
This one will work. You can take a look at the manual on the HF site. Do you have the workshop manual? A CIS manual is really useful also.
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06-07-2009, 03:52 PM
#8
Drifting
06-07-2009, 04:46 PM
#10
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IIRC the initial setting for CIS is as follows, with a couple of safety steps thrown in:
1) Jumper the fuel pump
2) Turn the A/F mix screw(@ front of fuel distributor) until you can hear the injectors squealing
3) Turn the A/F mix screw back until the injectors just about stop squealing
4) Remove fuel pump jumper
5) Disconnect green wire near ignition box
6) Remove plugs
7) Crank engine to clear any fuel from cylinder
8) Replace plugs
9) Reconnect green wire
10) Try to start
Step 7 is to make sure you don't get hydrolock if you took too long with steps 1-4
Step 5 is to ensure you don't start a fire at step 7.
If you didn't change the WUR setting or put the pressure regulator together improperly or with the wrong shims the car should now run.
I think there may be something else going on though, since that screw only affects idle. There is a quickie writeup for initial troubleshooting on Nichols.
1) Jumper the fuel pump
2) Turn the A/F mix screw(@ front of fuel distributor) until you can hear the injectors squealing
3) Turn the A/F mix screw back until the injectors just about stop squealing
4) Remove fuel pump jumper
5) Disconnect green wire near ignition box
6) Remove plugs
7) Crank engine to clear any fuel from cylinder
8) Replace plugs
9) Reconnect green wire
10) Try to start
Step 7 is to make sure you don't get hydrolock if you took too long with steps 1-4
Step 5 is to ensure you don't start a fire at step 7.
If you didn't change the WUR setting or put the pressure regulator together improperly or with the wrong shims the car should now run.
I think there may be something else going on though, since that screw only affects idle. There is a quickie writeup for initial troubleshooting on Nichols.
Last edited by SharkSkin; 06-08-2009 at 02:30 PM.
06-07-2009, 07:46 PM
#11
Drifting
06-08-2009, 10:39 AM
#12
IIRC the initial setting for CIS is as follows, with a couple of safety steps thrown in:
1) Jumper the fuel pump
2) Turn the idle mix screw until you can hear the injectors squealing
3) Turn the idle mix screw back until the injectors just about stop squealing
4) Remove fuel pump jumper
5) Disconnect green wire near ignition box
6) Remove plugs
7) Crank engine to clear any fuel from cylinder
8) Replace plugs
9) Try to start
Step 7 is to make sure you don't get hydrolock if you took too long with steps 1-4
Step 5 is to ensure you don't start a fire at step 7.
If you didn't change the WUR setting or put the pressure regulator together improperly or with the wrong shims the car should now run.
I think there may be something else going on though, since that screw only affects idle. There is a quickie writeup for initial troubleshooting on Nichols.
1) Jumper the fuel pump
2) Turn the idle mix screw until you can hear the injectors squealing
3) Turn the idle mix screw back until the injectors just about stop squealing
4) Remove fuel pump jumper
5) Disconnect green wire near ignition box
6) Remove plugs
7) Crank engine to clear any fuel from cylinder
8) Replace plugs
9) Try to start
Step 7 is to make sure you don't get hydrolock if you took too long with steps 1-4
Step 5 is to ensure you don't start a fire at step 7.
If you didn't change the WUR setting or put the pressure regulator together improperly or with the wrong shims the car should now run.
I think there may be something else going on though, since that screw only affects idle. There is a quickie writeup for initial troubleshooting on Nichols.
Dave,
Steps 2 and 3 above should reference the A/F mixture screw rather than the idle screw.
Dennis
06-08-2009, 10:47 AM
#13
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before you start buying/rebuilding/replacing things, test the pressures and volume test the fuel pump.
Ben Watsons book "How to Tune and Modify Bosch Fuel Injection" is a valuable resource. Pick one up.
Ben Watsons book "How to Tune and Modify Bosch Fuel Injection" is a valuable resource. Pick one up.
06-08-2009, 10:48 AM
#14
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Can you keep it running by pushing or pulling on the CO adjustment screw at the fuel distributor?
The 3MM adjustment screw is what I am talking about.
The fuel distributors rarely fail outright, some will leak but I do not think I have ever had to replace one because it had failed and it could not run.
Have you pulled all the injectors, bridged the pump relay and moved the plate to see what kind of a spray pattern you are getting?
I also would remove the plugs before cranking with the ignition system disabled if I had ran it long, fuel will build up in the cylinders and hydrolock a engine with CIS.
bottom line is you need the factory manual and knowledge of how a CIS works to repair one.
Not many have these skills anymore.
Just my $.02
The 3MM adjustment screw is what I am talking about.
The fuel distributors rarely fail outright, some will leak but I do not think I have ever had to replace one because it had failed and it could not run.
Have you pulled all the injectors, bridged the pump relay and moved the plate to see what kind of a spray pattern you are getting?
I also would remove the plugs before cranking with the ignition system disabled if I had ran it long, fuel will build up in the cylinders and hydrolock a engine with CIS.
bottom line is you need the factory manual and knowledge of how a CIS works to repair one.
Not many have these skills anymore.
Just my $.02
06-08-2009, 02:01 PM
#15
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