Author Topic: 1984 250 Fuel Issue?  (Read 1323 times)

Offline jbsealy

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1984 250 Fuel Issue?
« on: April 26, 2020, 10:29:41 PM »
Here's the history. I have a 1984 C10 SB 6 cyl. Three on the tree. Completely stock.  I have redone the brakes, replaced the leaking power steering gear and the steering shaft and coupler, rebuilt the heater, replaced a wheel well and repaired vacuum lines. Also had the three on the tree steering column rebuilt.  Engine is 100% stock. I have neglected this truck since I bought it used in 1985. I would really appreciate some help.  Before I repaired the vacuum lines the truck had a pronounced stumble on acceleration.  Vacuum lines did not fully change this but it ran better. I have driven this truck for several months on and off. The last time I had it on the highway I barely got home.  If I tried to accelerate the engine would die.  I was near home and feathered it back to the garage.  Now it is more difficult to crank and I can hardly get it out of the garage.  I can get it started but if I then try to get the revs up, it dies.  Your thoughts and advice would be appreciated.

Offline bd

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Re: 1984 250 Fuel Issue?
« Reply #1 on: April 26, 2020, 11:15:31 PM »
If you're having trouble cranking the engine, have the battery tested.  Make sure the cable ends are clean, tight and properly secured to the starter solenoid B+ stud.

Verify that you have >5 gallons of fresh fuel in the tank and check the fuel filter for restrictions.  Collect some fuel from the tank in a see-through container and let it sit for a few hours then inspect to make sure it hasn't separated into layers or is otherwise milky.

When was the last tune-up performed?  Test for a consistent, assertive blue spark using a proper HEI spark tester...





Check the base timing if you can get it started and running at a stable idle RPM.  Make sure the distributor clamp is tight and the distributor is not rotated with the vacuum advance pointing in an odd direction.

Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline jbsealy

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Re: 1984 250 Fuel Issue?
« Reply #2 on: April 27, 2020, 08:14:42 AM »
Thanks bd,

I often use the work crank and start synchronously, a mistake on my part as it can be confusing.  The truck cranks fine and starts.  It has been more difficult to start since this new problem.  The truck starts and will run a very few seconds and then die.  If I start it and try to increase revs, it dies.  Based on some of your recommendations I am thinking fuel filter.  I have been driving the truck fairly regularly with no problems until now and have added gasoline a time or two.  I don't think it is degraded gas.  I just filled up not long ago.  I will check the fuel filter at the carburetor.

Thanks for taking the time to respond.

JS

Offline bd

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Re: 1984 250 Fuel Issue?
« Reply #3 on: April 27, 2020, 09:46:08 AM »
...I don't think it is degraded gas.  I just filled up not long ago.  I will check the fuel filter at the carburetor.

By all means, check the fuel filter.  Remove the check valve and blow through it.  If there is any resistance, replace it.  But, don't disregard the potential for bad gas.  A gas station with water in its tanks is not unprecedented.  Did the symptoms begin shortly after fueling your vehicle? 

You didn't say how many miles have accumulated since the last tune-up.  Check the cap, rotor and a couple of spark plugs.  In addition, when an ignition control module or pickup coil fail, symptoms can be similar to those you are experiencing.  Checking the ignition using the HEI tester recommended earlier is a simple and effective go-no-go test.  Sparks should be blue in color, definite and maintain a consistent, rhythmic arc with engine cranking.

Regarding the longstanding hesitation from a stop, verify that the vacuum advance actually holds vacuum and that it rotates the pickup coil stator inside the distributor when vacuum is applied.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline jbsealy

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Re: 1984 250 Fuel Issue?
« Reply #4 on: April 28, 2020, 07:07:52 AM »
bd,

Thank you.  I checked the fuel filter and it looks good. The problem did not occur immediately but ~20 miles of driving after a fill up. So it might be the problem. Is there a drain on the tank? The last tune up may have been at the factory in 1984 ;D.  The diagnostic steps you suggest other than check spark are not things I am familiar with.

I will check all you have suggested and let you know.  I have the FSM.  I am considering a replacement distributor and wires and a rebuilt carburetor.  My skill level unfortunately is at the replacing parts level.

Thank you again for taking the time to help me out.

JS