No Start Problem
04-10-2022, 03:48 PM
#31
Pro
Thread Starter
04-10-2022, 05:56 PM
#33
Pro
Thread Starter
sure. Wouldn't this be solved when I press the gas? More air mixed with the excessive fuel pressure would make them cancel out right? Maybe I'm wrong in my thought process though.
Last edited by Acantor; 04-10-2022 at 05:58 PM.
04-10-2022, 06:09 PM
#34
Burning Brakes
It should never be that high. Since the oxygen sensor is not warmed up on startup, the ECU uses a fixed algorithm to meter how much fuel to inject. With the pressure 50% high, it is putting 50% too much fuel in the mixture. This may or may not be the only problem you have, but it is definitely a problem. Since this problem could be causing the symptom, I'd fix it first before spending time on other things. Clark's says about 36psi with the fuel pump jumpered and engine not running, 29psi when idling. Good luck!
http://www.clarks-garage.com/shop-manual/fuel-01.htm
http://www.clarks-garage.com/shop-manual/fuel-01.htm
04-10-2022, 06:12 PM
#35
I personally would not think that a extra 10 PSI would really give you the problems that you are dealing with but it might. I know you where searching for a regulator in the past if Im not mistaken what did you come up with. You could also pull a couple of spark plugs and take a look so see if they are really wet or possibly the opposite.
04-10-2022, 06:59 PM
#36
Pro
Thread Starter
Ok yeah even though I don't think that it is causing my issue, I will be replacing it because it is reading higher than the maximum for the regulator (according to Clark's garage). I replaced the damper with a new to me one (used) because it was leaking from the pinch connection. It doesn't seem to be too rare or expensive as the damper was so I will get on that soon. I will also try to test all my air determining sensors this week.
04-10-2022, 09:34 PM
#37
Just be methodical as you go. Simply put if it had a carb then no biggie but with the old weird DME theres room for issues. Back in the posts there where part numbers on things you might find that same number fits a 1988 Volvo so take a big breath and see what you can work out. Probably save some $.
04-11-2022, 12:26 PM
#40
Rennlist Member
I've been away for a week and am catching up.
I agree with Gasngo, I do not think high fuel pressure alone will keep the car from idling. You can intentially adjust a carburator rich and you will get this crappy exhaust note, etc but it won't keep the car from idling.
I have a key quesiton for you to consider. Does the car fire and try to run when the starter is engaged and then, after you release the key to the run position, die within a few seconds? Or does it run for say 5 to 10 seconds (or longer) and then die?
I agree with Gasngo, I do not think high fuel pressure alone will keep the car from idling. You can intentially adjust a carburator rich and you will get this crappy exhaust note, etc but it won't keep the car from idling.
I have a key quesiton for you to consider. Does the car fire and try to run when the starter is engaged and then, after you release the key to the run position, die within a few seconds? Or does it run for say 5 to 10 seconds (or longer) and then die?
04-11-2022, 03:05 PM
#41
Pro
Thread Starter
Last edited by Acantor; 04-11-2022 at 09:46 PM.
04-11-2022, 09:55 PM
#42
Pro
Thread Starter
I just tested the AFM and the results came up as follows:
Battery voltage: 12.57V
Voltage from terminals 6 to 9: 4.98V
Voltage from terminals 6 to 7: 87mV
Sensor plate (barn door): reads just a little under 4.98V at around 4.25V
Temperature sensor (intake air temp): 902-1,086ohms
Everything was done in accordance with Clark's Garage and with multiple testers.
I am at a loss right now and not quite sure where to go from here. Does the low voltage reading mean that I need to re wire the entire thing or is this a symptom of something else?
Battery voltage: 12.57V
Voltage from terminals 6 to 9: 4.98V
Voltage from terminals 6 to 7: 87mV
Sensor plate (barn door): reads just a little under 4.98V at around 4.25V
Temperature sensor (intake air temp): 902-1,086ohms
Everything was done in accordance with Clark's Garage and with multiple testers.
I am at a loss right now and not quite sure where to go from here. Does the low voltage reading mean that I need to re wire the entire thing or is this a symptom of something else?
Last edited by Acantor; 04-11-2022 at 09:56 PM.
04-12-2022, 10:03 AM
#43
Rennlist Member
OK, the reason I asked my question is that once you release the key, certain parameters, mainly a minimum rpm, must be met for the car to keep running. If the parameters are not met, the fuel pump is turned off, via the infamous DME relay. I think it takes just a bit for the fuel pressure to bleed off and stop the car. I always try and hook up, for diagnostic purposes, a fuel pressure gauge at the fuel rail and some sort of device that indicates spark. The cleanest way is to get an inductive timing light and wrap the sensor around the lead coming out of the coil. You have to be attentive and probably need a helper but you can watch both and see if the fuel pressure fades off or if you loose spark as you try and start the car. Also, listen to with a stethescope (or rubber hose) or just feel with your fingers the injectors to see if they are "clicking". This can narrow down your options.
I think the AFM is not critical. Under cold idle, the idle bypass circuit is kind of ruling the idle mixture. I'm sure you mentioned at some point but what year car is this? Up to 85.5, it is just a dumb device mounted under the manifold that starts out wide open and then gradually shuts off the air flow as it is heated up. The later cars have the ISV, which is a little more complicated. There is a world where you just put in a straight pipe for the device and see if the car will idle. It will idle high but thats OK. Before I did this, remove the air filter element and see if the car idles for more than a few seconds with starting fluid sprayed into the square opening upstream of the AFM. This may also give some clues. If it helps, you have probably ruled out ignition/spark issues.
It is reported that the cars will run in a limp home mode with the AFM disconnected. Try starting it with the AFM plug disconnected.
Not to insult you but be sure you have hooked all the spark plug wires up correctly. I would set the car at TDC as indicated by the viewing port at the flywheel. Pull the distributor cap and make sure the rotor is pointing to the plug wire that you have routed to the #1 cylinder. And the go from there. I don't have the firing order in my brain but it is pretty easy to find in online resources.
Pull the plugs and confirm that each sparks when cranking with the threads of the plug laying against a good ground. Check the plugs immediately after an attempt to start and see if they are wet or dry.
Make sure you hear the "click" at the throttle valve switch when you go from closed throttle to slightly open throttle.
It is a hail mary but if you can swap in a borrowed DME, that will rule it out. I did have a car that wouldn't start/idle and it was a bad DME. If it comes up, I am pretty sure you can't hurt a borrowed DME doing this. Disconnect the battery when swapping out the DMEs. You don't need to mount it, just get the plug off yours and attach it to the borrowed DME.
So there are some things to try.
I think the AFM is not critical. Under cold idle, the idle bypass circuit is kind of ruling the idle mixture. I'm sure you mentioned at some point but what year car is this? Up to 85.5, it is just a dumb device mounted under the manifold that starts out wide open and then gradually shuts off the air flow as it is heated up. The later cars have the ISV, which is a little more complicated. There is a world where you just put in a straight pipe for the device and see if the car will idle. It will idle high but thats OK. Before I did this, remove the air filter element and see if the car idles for more than a few seconds with starting fluid sprayed into the square opening upstream of the AFM. This may also give some clues. If it helps, you have probably ruled out ignition/spark issues.
It is reported that the cars will run in a limp home mode with the AFM disconnected. Try starting it with the AFM plug disconnected.
Not to insult you but be sure you have hooked all the spark plug wires up correctly. I would set the car at TDC as indicated by the viewing port at the flywheel. Pull the distributor cap and make sure the rotor is pointing to the plug wire that you have routed to the #1 cylinder. And the go from there. I don't have the firing order in my brain but it is pretty easy to find in online resources.
Pull the plugs and confirm that each sparks when cranking with the threads of the plug laying against a good ground. Check the plugs immediately after an attempt to start and see if they are wet or dry.
Make sure you hear the "click" at the throttle valve switch when you go from closed throttle to slightly open throttle.
It is a hail mary but if you can swap in a borrowed DME, that will rule it out. I did have a car that wouldn't start/idle and it was a bad DME. If it comes up, I am pretty sure you can't hurt a borrowed DME doing this. Disconnect the battery when swapping out the DMEs. You don't need to mount it, just get the plug off yours and attach it to the borrowed DME.
So there are some things to try.
Last edited by harveyf; 04-12-2022 at 10:07 AM.
04-12-2022, 10:15 AM
#44
Drifting
OK, the reason I asked my question is that once you release the key, certain parameters, mainly a minimum rpm, must be met for the car to keep running. If the parameters are not met, the fuel pump is turned off, via the infamous DME relay. I think it takes just a bit for the fuel pressure to bleed off and stop the car. I always try and hook up, for diagnostic purposes, a fuel pressure gauge at the fuel rail and some sort of device that indicates spark. The cleanest way is to get an inductive timing light and wrap the sensor around the lead coming out of the coil. You have to be attentive and probably need a helper but you can watch both and see if the fuel pressure fades off or if you loose spark as you try and start the car. Also, listen to with a stethescope (or rubber hose) or just feel with your fingers the injectors to see if they are "clicking". This can narrow down your options.
I think the AFM is not critical. Under cold idle, the idle bypass circuit is kind of ruling the idle mixture. I'm sure you mentioned at some point but what year car is this? Up to 85.5, it is just a dumb device mounted under the manifold that starts out wide open and then gradually shuts off the air flow as it is heated up. The later cars have the ISV, which is a little more complicated. There is a world where you just put in a straight pipe for the device and see if the car will idle. It will idle high but thats OK. Before I did this, remove the air filter element and see if the car idles for more than a few seconds with starting fluid sprayed into the square opening upstream of the AFM. This may also give some clues. If it helps, you have probably ruled out ignition/spark issues.
It is reported that the cars will run in a limp home mode with the AFM disconnected. Try starting it with the AFM plug disconnected.
Not to insult you but be sure you have hooked all the spark plug wires up correctly. I would set the car at TDC as indicated by the viewing port at the flywheel. Pull the distributor cap and make sure the rotor is pointing to the plug wire that you have routed to the #1 cylinder. And the go from there. I don't have the firing order in my brain but it is pretty easy to find in online resources.
Pull the plugs and confirm that each sparks when cranking with the threads of the plug laying against a good ground. Check the plugs immediately after an attempt to start and see if they are wet or dry.
Make sure you hear the "click" at the throttle valve switch when you go from closed throttle to slightly open throttle.
It is a hail mary but if you can swap in a borrowed DME, that will rule it out. I did have a car that wouldn't start/idle and it was a bad DME. If it comes up, I am pretty sure you can't hurt a borrowed DME doing this. Disconnect the battery when swapping out the DMEs. You don't need to mount it, just get the plug off yours and attach it to the borrowed DME.
So there are some things to try.
I think the AFM is not critical. Under cold idle, the idle bypass circuit is kind of ruling the idle mixture. I'm sure you mentioned at some point but what year car is this? Up to 85.5, it is just a dumb device mounted under the manifold that starts out wide open and then gradually shuts off the air flow as it is heated up. The later cars have the ISV, which is a little more complicated. There is a world where you just put in a straight pipe for the device and see if the car will idle. It will idle high but thats OK. Before I did this, remove the air filter element and see if the car idles for more than a few seconds with starting fluid sprayed into the square opening upstream of the AFM. This may also give some clues. If it helps, you have probably ruled out ignition/spark issues.
It is reported that the cars will run in a limp home mode with the AFM disconnected. Try starting it with the AFM plug disconnected.
Not to insult you but be sure you have hooked all the spark plug wires up correctly. I would set the car at TDC as indicated by the viewing port at the flywheel. Pull the distributor cap and make sure the rotor is pointing to the plug wire that you have routed to the #1 cylinder. And the go from there. I don't have the firing order in my brain but it is pretty easy to find in online resources.
Pull the plugs and confirm that each sparks when cranking with the threads of the plug laying against a good ground. Check the plugs immediately after an attempt to start and see if they are wet or dry.
Make sure you hear the "click" at the throttle valve switch when you go from closed throttle to slightly open throttle.
It is a hail mary but if you can swap in a borrowed DME, that will rule it out. I did have a car that wouldn't start/idle and it was a bad DME. If it comes up, I am pretty sure you can't hurt a borrowed DME doing this. Disconnect the battery when swapping out the DMEs. You don't need to mount it, just get the plug off yours and attach it to the borrowed DME.
So there are some things to try.
Last edited by T&T Racing; 04-12-2022 at 10:18 AM.
04-12-2022, 01:20 PM
#45
Pro
Thread Starter
I have ordered a new Fuel Pressure regulator, I will replace this first before testing what you guys have suggested to keep everything consistent.