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Discussion Starter · #1 ·
Going to start from start of problems. Bike sat in garage a little more then a year. Started with no problem. Bike kept loosing power like starving for gas. Rust in gas tank. Red Kote the tank. Bike ran fine but still lack of power. Clogged injectors. Replaced injectors. Then bike was not firing on front cylinder. Replaced both coils and wires. New plugs. New air filter. Bike again ran fine, but, again still lacked power. Then coil pack went on front cylinder again. Honda would not replace and was on for 7 months. Bought two more coils. After coil replacement front cylinder still not firing. Started troubleshooting. Checked injection continuity and ok. Checked spark and ok. Replaced fuel pump. Checked all fuses. Found ECM fuse blown. Replaced fuse. Still not start. But did see smoke. Bad ECM. Replaced ECM and bike fired right up. Test drove and wow it had power. Brought home and next day went for a test ride. All good for 36 miles. Wife and I went to daughter house 26 miles away. Pulled in driveway and as turning in driveway bike stalled slowly like running out of fuel. Had little more than half tank. Will not start. Put on trailer and brought home. Checked bank sensor and good. Checked CKP sensor and good. Checked Ignition switch and kill switch and good. Checked side stand switch and good. Battery fully charged while testing.
Decided to check error codes, well, should have done that first. Had an DTC error 13 which is front injector. Checked voltage and 3.3 volts. Supposed to be 12v. I cleared the error code and reset the ECM.
I have not gone past this point. So frustrated with all this testing. I am thinking it is the ECM. It was not new but used.
I do have the service manual and have been following it all over the place.
 

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A few guys had the fuel pump go bad especially after riding a while and it got warm .
It is hard to test the pressure on a EFI system since it is about 50 pounds and has special locking fittings. But it can be done with a gauge set with the fittings.
Maybe not the issue but good to know about that. There is a sock type fuel filter around the pump and that may be clogging up.
Make sure the battery terminals and very clean and tight. And the engine and frame grounds are the same way. You can always add grounds to make sure there is no deficiency from that.
Measure the battery voltage, running 13.5 to 14.5 volts revved up. EFI is sensitive to battery power.
Did find that 3.3 volts with the injector unplugged? And compared to the other one?
With a stethoscope, you can listen to the injectors even cranking and see if they both sound about the same = clicking.
 

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Discussion Starter · #3 ·
A few guys had the fuel pump go bad especially after riding a while and it got warm .
It is hard to test the pressure on a EFI system since it is about 50 pounds and has special locking fittings. But it can be done with a gauge set with the fittings.
Maybe not the issue but good to know about that. There is a sock type fuel filter around the pump and that may be clogging up.
Make sure the battery terminals and very clean and tight. And the engine and frame grounds are the same way. You can always add grounds to make sure there is no deficiency from that.
Measure the battery voltage, running 13.5 to 14.5 volts revved up. EFI is sensitive to battery power.
Did find that 3.3 volts with the injector unplugged? And compared to the other one?
With a stethoscope, you can listen to the injectors even cranking and see if they both sound about the same = clicking.
Does not have sock type in the sub fuel housing. Filter and pump are brand new and did test the pressure at 48lbs. Also cranked and watched the fuel shoot out. No fuel problem. Battery voltage when was running was between what you stated when rad fan kicked on only dropped .3v. Yes the injector was unplugged when checking the voltage. Did not have time to check the other one as it started raining and had to cover it. Will check it in morning. Battery terminals are brand new clean and have them covered with petroleum jelly. Will also check for clicking as I have a stethoscope.
 

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Discussion Starter · #4 ·
Does not have sock type in the sub fuel housing. Filter and pump are brand new and did test the pressure at 48lbs. Also cranked and watched the fuel shoot out. No fuel problem. Battery voltage when was running was between what you stated when rad fan kicked on only dropped .3v. Yes the injector was unplugged when checking the voltage. Did not have time to check the other one as it started raining and had to cover it. Will check it in morning. Battery terminals are brand new clean and have them covered with petroleum jelly. Will also check for clicking as I have a stethoscope.
Okay, I found the problem after going and tracing other sensors like IAC, MAP and more. Found what I suspected when posted what it was, ECM. Now to find one at a freaking fair price.
 

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I keep thinking about your 3 volt measurement on one injector and 12 volts on the other. Both injectors when unplugged should have battery volts on the black/white wires. Both are the same connection from the ignition.
So if one has low voltage unplugged it has to be a wiring problem with a bad connection or resistance somehow.
You are measuring from the black/white wire to ground correct?
The other wire at the injector is the grounding pulse from the power transistor to fire it. That is not a place to measure.
 

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Another thing to do is measure the resistance of the injectors and compare to each other.
The manual show 11 to 13 ohms as normal.
 

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Discussion Starter · #7 ·
Another thing to do is measure the resistance of the injectors and compare to each other.
The manual show 11 to 13 ohms as normal.
I had 12 ohm at both resistors. I am at error on the voltage because storm was coming and trying to hurry to cover the bike. When rechecked in the morning, first thing, they were both battery voltage. I am ordering an new pgm-fi unit in the morning as soon as I get a reply from the company about a warranty on it. Found it new for $462.53. PN 38770-meg-a62.
Thanks for your help Swifty, I know where to come back to for questions if I have any. My first bike was a new 1978 Honda CM400T. It was stolen in 83. Then got a new 1982 Honda CB750Custom. Rode it year round and got caught in snow once with it. Put over 100,000 miles on it. Lowest temp I rode one night home from work at 2am was 11 degrees.
Thanks again for your help.
 

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Discussion Starter · #8 ·
I had 12 ohm at both resistors. I am at error on the voltage because storm was coming and trying to hurry to cover the bike. When rechecked in the morning, first thing, they were both battery voltage. I am ordering an new pgm-fi unit in the morning as soon as I get a reply from the company about a warranty on it. Found it new for $462.53. PN 38770-meg-a62.
Thanks for your help Swifty, I know where to come back to for questions if I have any. My first bike was a new 1978 Honda CM400T. It was stolen in 83. Then got a new 1982 Honda CB750Custom. Rode it year round and got caught in snow once with it. Put over 100,000 miles on it. Lowest temp I rode one night home from work at 2am was 11 degrees.
Thanks again for your help.
oops 12 ohms across both injectors. Even got out the old ones and checked at the same resistance. Just have to clean them and have spares. :) When cleaned them they were clicking when applied power to them to clean.
 

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Discussion Starter · #9 ·
oops 12 ohms across both injectors. Even got out the old ones and checked at the same resistance. Just have to clean them and have spares. :) When cleaned them they were clicking when applied power to them to clean.
Okay, starting from scratch again. At wits end. Got the new ECM. Put it in and will not start. I can crank the starter a few times, about only 2 second intervals and it will start but only for 2 seconds and stall. While trying to start when it did run the pipes got warm so both cylinders are firing. What I have checked so far again. Have good spark. Has gas. Fuel pump pumping fuel to injectors.
 

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They have to have 50 pounds pressure fuel pressure. The pump may be tired and low pressure.
OOPS I SEE YOU TESTED IT.
Do you hear a nice smooth hum from the pump or are there noises?

Do the injectors click while cranking?
 

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Discussion Starter · #11 ·
They have to have 50 pounds pressure fuel pressure. The pump may be tired and low pressure.
OOPS I SEE YOU TESTED IT.
Do you hear a nice smooth hum from the pump or are there noises?

Do the injectors click while cranking?
Tested pump yes, but also brand new fuel pump. Pump has smooth humm on key on and also when stop cranking. I will check to see if the new injectors are clicking in morning.
 

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It may be hard to hear while cranking but a stethoscope or long screwdriver may work.
 

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Discussion Starter · #13 ·
It may be hard to hear while cranking but a stethoscope or long screwdriver may work.
I have clicking while cranking. I also removed the injectors and assembled it back together out of the bike and cranked it and gas is spraying out of both injectors.
I also am getting a maybe 2 second startup. In other words if I crank the starter for 30 seconds continuous it shows no sign of starting at all even giving it the throttle. Now, if I crank it for 3 seconds and stop and repeat for about 4 or 5 times it will start, runs for 2 seconds and dies.
 

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Almost sounds like the pump is priming and then when you go to start it is not getting the continue to pump signal.
If you take off the fuel return hose from the fuel rail that goes back to the fuel tank, and have it going in a container you can watch when the pump is working.
You could watch when the fuel pressure is there and when it quits.
Easy test anyway.

If that is working fine maybe spark quitting?
Do you have an old timing light to hook to a spark plug wire and watch spark at all times?
Or one or two of these are very handy.

 

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Discussion Starter · #15 ·
Almost sounds like the pump is priming and then when you go to start it is not getting the continue to pump signal.
If you take off the fuel return hose from the fuel rail that goes back to the fuel tank, and have it going in a container you can watch when the pump is working.
You could watch when the fuel pressure is there and when it quits.
Easy test anyway.

If that is working fine maybe spark quitting?
Do you have an old timing light to hook to a spark plug wire and watch spark at all times?
Or one or two of these are very handy.

Lost me on fuel rail. I know which one is the fuel return line from the sub fuel tank to the tank or as the manual states the fuel vapor return hose. Is this the line your talking about? If I take the line off the tank drains. I installed on each line a brass shutoff valve so when I take the tank off I don't have to drain it all the time.
I do have a timing light, lol, 4 of them. Will hook one up and see what I got.
To let you know also the parts that are brand new that I replaced since the start of this mess is;
Injectors
fuel pump
coils (twice) One went bad, so bought another set and also new wires.
ECM
spark plugs
Note also, when I did short crank it and it started then stalled, I did this a few times to make sure that both cylinders were firing, both pipes got warm. This tells me that both are firing.
 

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I may not be helping here as I was thinking of the car system with a fuel rail return line back to the main tank.
It looks like these have a return hose similar but right back up into the tank.
It still may work the way I described, but you have to plug off the tank nipple and then put the hose into a container.
Just a wild ass guess.
 

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Discussion Starter · #17 ·
I may not be helping here as I was thinking of the car system with a fuel rail return line back to the main tank.
It looks like these have a return hose similar but right back up into the tank.
It still may work the way I described, but you have to plug off the tank nipple and then put the hose into a container.
Just a wild ass guess.
I did the timing light and tach test on crank. All are working fine. I took the tank off today to start all the troubleshooting. I got the TP sensor first and all is fine except the last test. The yellow/red wire when I check the wire harness to ground continuity I do have 220.49 and manual says should be none. Cannot understand the ground because that wire according to the wire diagram goes to what looks like a connector but no in or out, like a dead end. Will this stop the bike from starting?
Checked the fuel pump with two containers, one in one out. It continually pumps fuel out while cranking.
I also checked all three relays, fan control, fuel cutoff and engine stop. All good.
Going to check the IACV tomorrow. Did hear it clicking though when turn on the key. Is it supposed to click? Will find out if bad in morning.
 

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I don't see any direct ground connection on the diagram for TPS. Looks like it connects to several sensors.

The IACV may make a sound as the ECM sets it ready for starting. Should be able to watch it with intake off.
 

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Discussion Starter · #19 ·
I don't see any direct ground connection on the diagram for TPS. Looks like it connects to several sensors.

The IACV may make a sound as the ECM sets it ready for starting. Should be able to watch it with intake off.
I troubleshoot the IACV and the last test showed it bad. I took it out and ran it out holding the outside plastic like the pin does inside and it moved very little. It is loosing up on the screw center shaft. Don't know if supposed tp be tight or not. Think not cause it has to slide up and down and rotate up and down the threads.
The tp sensor according to the diagram is not right as mine has 5 wires. I looked at the main wiring diagram of everything to see where that wire went to.
Any way, I ordered a IACV, cost was $90 and won't have for 2 weeks like the ECM because coming from the same place.
I did email them asking about the time issue as the ECM only has a 30 day warranty. The ECM is not out of the woods yet until I troubleshoot the rest of it to make sure it is good. So far this time everything I am retesting is not giving me faulty ECM or replace with a known good one. Going to continue checking on to the next step though which I have to see what's next if IAVC was good.
 
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