Fuel help please

[delorean82]

Ok Guys I could really use some great technical advice.

My car runs Rich, as of this weekend i was getting 17 MPG approx. And it smells really bad. I decided to adjust the fuel mixture and ended up making it worse. I cliped the dwell meter to the orange connection on the black diag plug and ground at the engine valve cover. The meter read 46, its doubled because its on a 8 cylinder scale. so it really read 23. RPMs around 775-800. The car at idol seems to surge up and down, but not really hunt like our cars do. i could not get the meter to move in any direction while adjusting the mixure screw. The o2 sensor was pluged in and the car was at normal operating temp. I checked the idol control valve and it feels like its working.

Here is what has been done, A year ago i replaced the plugs, wires, dist cap and rotor, intake o rings and just got the injectors back from a cleaning and replaced the o rings in the PPR of the fuel distributor. While the injectors were out i placed the lines in small mason jars to check to see if the fuel comming out was consistent in all cylinders. I found that cyl 1-3 filled the jars about a half inch while 4-6 filled the jars a quarter inch full. I've studied every scrap in information i can find on this system to understand how it works. I really want to fix it myself and gain the trouble shooting skills to know what to check.
Does any one have any idea as to what may be going wrong? I think the WUR is at fault and or the fuel distributor. The car runs strong, just rich and with out a good idol.

[WelmoedJ]

Ok Guys I could really use some great technical advice.

My car runs Rich, as of this weekend i was getting 17 MPG approx. And it smells really bad. I decided to adjust the fuel mixture and ended up making it worse. I cliped the dwell meter to the orange connection on the black diag plug and ground at the engine valve cover. The meter read 46, its doubled because its on a 8 cylinder scale. so it really read 23. RPMs around 775-800. The car at idol seems to surge up and down, but not really hunt like our cars do. i could not get the meter to move in any direction while adjusting the mixure screw. The o2 sensor was pluged in and the car was at normal operating temp. I checked the idol control valve and it feels like its working.

Here is what has been done, A year ago i replaced the plugs, wires, dist cap and rotor, intake o rings and just got the injectors back from a cleaning and replaced the o rings in the PPR of the fuel distributor. While the injectors were out i placed the lines in small mason jars to check to see if the fuel comming out was consistent in all cylinders. I found that cyl 1-3 filled the jars about a half inch while 4-6 filled the jars a quarter inch full. I've studied every scrap in information i can find on this system to understand how it works. I really want to fix it myself and gain the trouble shooting skills to know what to check.
Does any one have any idea as to what may be going wrong? I think the WUR is at fault and or the fuel distributor. The car runs strong, just rich and with out a good idol.

1. Cleaning of the D's injectors: These are injectors that open by pressure. Therefore proper cleaning can only be achieved if the cleaning device can open the injectors. Ultra-sonic cleaners can't and therefore are useless.

2. You found having different fuel quantities on several chambers of the FD. Therefore you should have to ensure the chambers produce (almost) equal quantities, otherwise you will keep having issues.
Mind that opening the FD by yourself may result in more trouble. Find a company that can rebuilt the FD to Bosch specs (I believe DPI can).

3. Not all of our cars hunt. Some of them do for a short period of time while warming up, other cars have a slight hunt while warm, some never hunt. Hunting usually is caused by the fuel mixture and can be corrected, provided the entire system is in good working order.

4. Are all fuel lines correctly installed, that is to the proper cylinder or other device in the chain?

BTW: By idol you hopefully don't refer to an actor or singer? I'm not English mother tongued, so I presume a slip of the pen and read it as "idle". No offense meant.

Hopefully you find this info usefull.

[David T]

Ok Guys I could really use some great technical advice.

My car runs Rich, as of this weekend i was getting 17 MPG approx. And it smells really bad. I decided to adjust the fuel mixture and ended up making it worse. I cliped the dwell meter to the orange connection on the black diag plug and ground at the engine valve cover. The meter read 46, its doubled because its on a 8 cylinder scale. so it really read 23. RPMs around 775-800. The car at idol seems to surge up and down, but not really hunt like our cars do. i could not get the meter to move in any direction while adjusting the mixure screw. The o2 sensor was pluged in and the car was at normal operating temp. I checked the idol control valve and it feels like its working.

Here is what has been done, A year ago i replaced the plugs, wires, dist cap and rotor, intake o rings and just got the injectors back from a cleaning and replaced the o rings in the PPR of the fuel distributor. While the injectors were out i placed the lines in small mason jars to check to see if the fuel comming out was consistent in all cylinders. I found that cyl 1-3 filled the jars about a half inch while 4-6 filled the jars a quarter inch full. I've studied every scrap in information i can find on this system to understand how it works. I really want to fix it myself and gain the trouble shooting skills to know what to check.
Does any one have any idea as to what may be going wrong? I think the WUR is at fault and or the fuel distributor. The car runs strong, just rich and with out a good idol.

If it is "running rich" and you did not mess with the mixture screw it means one or more cylinders is not firing properly and burning up the fuel. Adjusting the mixture screw affects all of the cylinders equally, including the one that isn't working. Most of the time it is because one or more injectors is dirty/bad pattern, leaking. It can also be an ignition problem, or maybe a valve needs adjustment. The motor won't hunt normally because the Lambda system is in "open loop" because the O2 sensor is getting fouled. Same for the idle system, if the motor is not running evenly on all 6 cylinders it will not be smooth. Pull the spark plugs and see which one (s) are black. Those will be from the cylinders not firing properly.
David Teitelbaum

[delorean82]

Thanks for the advice all.
When i did have the injectors cleaned they were pressure cleaned and checked for spray pattern, so i know the injectors are ok. All the fuel lines are connected correctly. The car used to hunt on start up but now does not. Im thinking ill try and replace the spark plugs and see how this affects the running of the engine. I do agree that unequal fuel quantity in the lines would be a faulty FD. I did have the valves checked for adjustment last year when the gaskets were changed and they were ok. Last night I tried to start the car and it started ok, but I noticed that the fans kicked on and stayed on before it even started. This problem sounds to me like a failed coolant sensor, it's just weird that it happened at the same time im having these other problems. I did try and adjust the fuel mixture to lean it out. Is there a better way to connect up the dwell meter? I don't understand why the meter dident move from its reading, like it was not hooked up right. Any ideas?

[Ron]

If the engine is cold and the fans are running, unplug either wire from the otterstat. If the fans quit, the otterstat is bad (shorted internally). Otherwise, you have wiring problems along the circuit from the otterstat to the fans...


The dwell sounds normal if the engine was cold (<59F), the dwell should not change until the engine is warm (steady 50°-60°).
SEE: D:04:15 in WorkShop Manual

[delornut]

If it is "running rich" and you did not mess with the mixture screw it means one or more cylinders is not firing properly and burning up the fuel. Adjusting the mixture screw affects all of the cylinders equally, including the one that isn't working. Most of the time it is because one or more injectors is dirty/bad pattern, leaking. It can also be an ignition problem, or maybe a valve needs adjustment. The motor won't hunt normally because the Lambda system is in "open loop" because the O2 sensor is getting fouled. Same for the idle system, if the motor is not running evenly on all 6 cylinders it will not be smooth. Pull the spark plugs and see which one (s) are black. Those will be from the cylinders not firing properly.
David Teitelbaum

To add to what David says here: When a cylinder is misfiring it's still pulling air through it and the unburned oxygen is picked up by the O2 sensor which then senses a lean mixture. This tells the ECU to enrich the mixture via the frequency valve.

Bruce Benson

[Rich]

....Last night I tried to start the car and it started ok, but I noticed that the fans kicked on and stayed on before it even started. This problem sounds to me like a failed coolant sensor, it's just weird that it happened at the same time im having these other problems.....

The condition you describe could be normal.

It will occur if the ignition key is either ON or ACC and if the A/C mode switch is in BiLevel, Norm or Max. with engine off. In that case the fans will come on as soon as you turn the key, even if your A/C circ fan switch is off and regardless of coolant temp.

Maybe you left the A/C on the last time you switched off the car. If you do that then it does this.