The Stovebolt Site Forums The Shop Area The HiPo Shop Gummed up injectors for my 1959 Chevy Truck

Thanks Otto

I am guessing the injectors are gummed up. When I pulled the fuel filter pure varnish came out. I need to figure out if it is better to clean them or replace them. We used to clean them when we had the garage. I grew up diagnosing problems but I don't have the luxury of having test equipment anymore. I really don't want to just start throwing parts at it.

The brakes are good to go. I replaced all four wheel cylinders. It already has a fairly new Corvette master cylinder.

Curtis: I moved your technical questions (and the answers to it) to here. Your Welcome Centre post then stays a "welcome" (has great potential to end up in the DITY Gallery. )

On tech questions, you'll get a lot of help in the The Shops Area.

As folks have said, pictures-pictures-pictures! We all like pictures!

If it's sat with ethanol blend fuel you likely have a mess. You mentioned injectors, do you have some kind of fuel injection system?

Yes it has TBI. The electrical, ignition, and fuel systems are from a '87 C-10

Has it sat with E10 in the tank?

I have a benchtop injector cleaner/tester that I use for that.

I will put the injectors in an ultrasonic bath for 5-10 min, then put it on the flow bench for 3 min to flush them with clean gas, then put them back in the cleaner, then reverse flush them.

If I ama feeling really fancy, I will do a flow test before and after the cleaning but I usually don't bother with the "before" anymore. Just run an after test with the whole set that I cleaned to make sure they are balanced.

I decided to just buy my own cleaner/tester because it was cheaper than paying for an LS set to get cleaned/tested. This is th style I have.

If you only have the 2 injectors, you could soak them in carb cleaner, use a battery to open them and blow them out with an air compressor. Do that a couple times, then clean/blow them out with fresh gas. The tbi system is fairly low pressure, so I would limit your air pressure to 12psi when blowing them out.

I don't know where he got gas for it but I am going to assume it was an ethanol blend. I have no idea how long it sat in the tank but it went bad sometime between summer 2021 and January 2022. I let the fuel pump pump out as much as it could and replaced the fuel filter. It will now idle and drive up to about 25mph. After that, it starts fading out. I leave it in gear and once it drops below 25mph it picks back up and starts running again. I am having difficulty getting it timed properly so there may be an issue there. Right now it is timed by ear because it will not run when I attempt to set it via timing light. It has the wire to disconnect to set timing but the computer still keeps moving the mark even though it is unplugged. It has been many years since I worked as a mechanic but I did remember that wire and that it was hidden on some trucks.

Before you go too much farther, I would throw a fuel pressure gauge on it and see if the fuel pressure is dropping off when you lose power. That sounds more like a pump failure than a dirty injector to me.

I have considered there may be a filter in the tank too. It has a tank from an Oldsmobile or Buick if I remember correctly. I need to research that.

If you would like a differnt set of injectors I have a TBI unit from a '91 350 that is sitting on the shelf collecting dust. You can have it for the cost of shipping. If interested send me a PM.

Thank you! I will pursue the earlier suggestions and if those don't work I may take you up on that offer.

Yes - and the Fuel Pressure regulators in those can go as well, which can cause similar issues. Has a flexible accelerator-pump like part that the spring bears on, which can crack; and a spring that can get weak or break. The FPR is inside the TBI unit but is easily repaired without completely removing the TBI unit as a whole, just have to remove the lines and IIRC 5 screws and the assembly lifts off. Make sure you get gaskets before you start.

Also - with an EFI swap of any sort: Check the sizing of your feed line (I'd recommend 3/8" for those) and make sure the return line routing is functional. There are some creative workarounds I've seen, some of which can work under most circumstances but that can cause issues over time or under load.

Back in the dark ages, some of us had a quick and dirty injector cleaning procedure. Remember the squeeze tool that was used to pierce a can of Freon for charging an air conditioning system? We would adapt one of those things to fit a spray can of carburetor cleaner, and attach the hose to the pressure monitoring port on a fuel injector rail. Disable the fuel injection pump, run the engine at a fast idle on straight carb/injector cleaner for the full volume of the can, and the injectors got squeaky clean. It was usually a pretty good idea to disconnect the catalytic converter to keep from poisoning the catalyst with the exhaust gas in the process.
Jerry

Update: I dropped the fuel tank and the inside is varnished . The sock on the end of the pick up is disintegrating. It is a new tank so it is not rust. I can clean what I can reach and it is nice and shiny but I can't get behind the baffles. I seem to remember back in the day people steamed cleaned them but the baffles would still be a problem.


Any suggestions?

Thanks

Curtis

I clean a fuel tank by putting a few gallons of a strong mixture of laundry detergent and water into the tank and several pounds of pea gravel, then strap the tank to a rear wheel on my tractor and bush-hog a pasture for a couple of hours. Strapping the gravel-filled tank down in a pickup bed and running a few miles on a twisty 2 lane road also does a pretty good job. Getting the gravel back out is somewhat of a chore, but not impossible.
Jerry

A gallon of acetone will dissolve the varnish. You just need to slosh it around so it covers all the inside surfaces.

Radiator shops around here will clean fuel tanks out the same way they do radiators.