Mechanics

VEHICLE STARTING ISSUE USUALLY DURING COLD STARTS

1986 Mitsubishi Mighty Max • 230,000 miles

86 Mitsubishi 5 speed 2wd pickup has an issue with starting. The truck use to start almost instantly (2-3 engine revolutions) upon turning ignition key. Now, some time ago it developed a starting problem where as it would take many many revolutions to start up. Usally in the morning or after a prolong sit this problem would be an issue. Another strange factor during these difficult starting periods is that it would sound like engine is running backwards for a few seconds on a few of the failed starts and as it stopped this short run, it would force air out carb. Factor two involves the starter motor during difficult starting, turning ignition key would often make the starter just click like a dead battery would do. Though, turning the key in the switch off, on, off, on, off, on would correct the problem in most cases, or would make starter crank very slowly. I repeated the key switch turning until the starter began to receive a full voltage from battery as so it seems. The vehicle will eventually start after several tries as mentioned aboved. Once getting vehicle started and warmed up after some driving, the starting issues seems to no longer be an issue. The vehicle will start almost instantly upon a turn of the key and runs just fine. I was told once that the vehicle was not receiving a full 12 volts during the start procedure. They explained the vehicle receives 12 volts during the initial start and after engine begins to run and key is relaxed to run position, the vehicle drops the voltage to around 9 volts to save coil from overheating. This seems kind of how it acts though, low voltage, hard starting, occassionally getting the 12 volts when I rotate key repeatidly until starter rotates at it's normal speed. Though, if the starter is turning rapidly like it should, it does not seem to have an effect on making the engine startup and run any quicker like it should.-Things I replaced while chasing this starting problem and have not fixed it so far.*Ignition switch-not recently, though it may be time for a new one again.*Complete starter-recent*Coil-recent*Weber Carb-recent-Vehicle History*Owned for 24 years with an excellent service maintenance and repair records. 90% of performed repairs were made by myself, so I know this vehicle very well, minus electrial issues which I am not to experienced at. *Mileage 230,000*Everything gets replaced that normally breaks down during day to day operation or had just stopped working correctly during the time I have owned this vehicle. Items that have not been replaced yet would be the lower engine block components and distributor. Your help would be very appreciated concerning my issues with this strange problem of engine starting. Thank you in advance for taking the time to view my request. I hope that I have explained my request for help in an understandible way that can be diagnosed. Thank You Again, Bradmph
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Bradmph
December 8, 2011.




Have the fuel pressure, valve and ignition timing check and the ignition switch-start here
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Tiny
Rasmataz
Dec 8, 2011.
Possibly a worn out distributor? Does that have a timing chain or belt?

Tiny
Fixitmr
Dec 8, 2011.
Rasmataz: The mechanical fuel pump has been replaced when I replaced Carb. I have also added to fuel line: *Fuel pressure mini-gauge(reads 3-4 consistantly)
*Fuel pressure adjuster. This is now manually adjustable since I replaced stock carb to a true weber carb. Yes the mechanical fuel pump was pumping too high for the weber. Before fuel adjustment, it was reading over 5 on the gauge until I installed the Fuel pressure adjuster.

Fixitmr: The truck has a rubber cogged belt for timing & oil pump, which both been replaced within the past 3 months. When timing belt broke, it some how caused the crankshaft pulley bolt to spin off with the pulley. Thank god the 2 parts just dropped onto the skid plate tray where I was able to retrieved them and install both new belts. I thought maybe timing belt jumped a tooth prior to the belt melt down. This would be a sure sign for hard starting and reverse carb air flow, but after replacement it did not start any easier.
The distributor: I am wondering about this part myself. I have looked at the distributor and while motor is not running, grabbed the rotor and checked side to side play. This didn't seem to be an issue since the play was almost null. I grabbed rotor again and turned it forward and backward to check the return action of the rotor shaft. This seemed to be a little stiff to return to home. It didn't snap back completely to home when I did this test. It looked like it returned a little shy of home. I have another distributor off of a wrecking yard truck that I picked up a while ago. This one seemed to be a little more springy when I performed the same rotor turn test on it.
But, would this cause the truck to have a hard start when cold from overnight sitting and start quick when warmed up and being used?

Tiny
Bradmph
Dec 10, 2011.
Is the choke opening and fast idle cam adjusted properly?

Tiny
Rasmataz
Dec 10, 2011.
Yes, choke works well and fast idle also. It was changed from the original water controlled choke to an electric choke when I replaced the stock carb with the new weber carb.

Tiny
Bradmph
Dec 13, 2011.

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