88IrocZProjectCar

I am in the process of getting my Iroc running after 20+ years (link above) of sitting on blocks in my garage. The tank was removed, cleaned and had a new high flow fuel pump installed for a 400-500hp 406sbc back in ~2000 and has been sitting. After deciding to go back to mostly stock, I've re-installed the fuel tank and fuel filter this month and my thoughts were to put a couple gallons of gas with high concentration of fuel injector cleaner in the tank and circulate it through the fuel rails and back through the return line that was disconnected and will dump back to a 1-gallon clear glass jug for inspection of contaminates. My thought is to power the fuel pump direct from a 12vdc battery to the electrical connection at the tank and control with a starter solenoid manual bypass switch I have. Here are some questions I've asked myself and are asking for any input.

• Obviously using an electrical switch connected to a battery is a concern. My thought was keep garage door open with fan running in front of car blowing out and keep battery and switch far away from open glass jug that's collecting the dirty fuel. There are probably dozens of ways to do this using separate clean fuel container, using manual pump, air pressure or vacuum, my 1st way seemed to be the simplest. I also thought about putting battery in car and using key to turn fuel pump on without starting, but I wasn't sure if when priming the pump if the relay times out and you have to keep turning the key on and off, or will pump stay on?
• I guess I have some concern of flushing debris past the injector inlets and through the back pressure regulator, so I had another thought of disconnecting the fuel line at front of car and just using a hose jumper from supply to return to flush just fuel lines. but then how do I clean fuel rails without taking everything apart. I realize I have may have to remove the injectors to clean anyway, but I am trying to minimize what I take apart. If I get everything clean through the fuel lines and rails, and the injectors aren't totally plugged, if I can get car started I may be able to use heavy doses of fuel injector cleaner to clean up injectors while driving.

I assume that people have had to go through this before from barn finds or vehicles just sitting like mine and hopped someone would share their experience of how the handled this problem.
Any comments or opinions appreciated.

 

The ECM will time out the fuel pump relay, after 2 seconds when using the key. I would run a jumper wire from the relay plug (or any good power source), to a switching device, where you'll be standing/laying to do the flush, and back to the relay plug...then you'll have complete control.

I wouldn't worry about fumes TOO much...the fact that you've given it thought, plus the fan is going to be way better than good enough.

I'd bet that you'll need to replace all 8 injectors. I'd bet that they're heavily varnished. But....I'd probably flush the system as you described, and then give it a whirl. No, I wouldn't worry about getting debris in the injectors; they have screens, and like I said, I bet they're toast anyway.

 

I totally agree about the stock injectors..without sitting for 20 years they're garbage. Coils may be bad...they may leak, or they may be clogged. Even if you get them to spray....you will not know if they are all flowing within spec or matched within reason

 

I look at it like you have two routes to go here. One requires more effort and money up front but is a much safer bet for long term reliability. The other way may be a little easier now but you could be asking for more trouble down the road.

The safest route would be to go ahead and take everything apart. Get a new tank, pump, pressure regulator and even fuel lines if needed. Your lines are probably ok but you never know until you run some air and/or fuel through the lines. You can do an initial clean out with compressed air if you have both sides of metal fuel line disconnected. Did you put a stock fuel pump back in? If not you probably want to, you don't need a bigger pump for the stock TPI, it will just create more heat. I agree with the others, the stock injectors are probably toast. If they do somehow still work, they will probably leak or fail soon. Fuel system components generally don't do well after sitting. Even if it runs ok initially things may start to fail as you use the car. If you start fresh with new parts and clean lines your odds of lingering issues are much lower.

If you want to try things out as it sits you can remove the fuel pump relay and install a jumper wire to power up the pump. I've done that before to empty out a tank of bad gas. If you need specifics I can look up a wiring diagram and tell you exactly what to do. If you do this disconnect the fuel line at the rail and put the hose into a bucket or bottle, if there are any debris in the lines you don't want them getting into the fuel rail and injectors. Once you see no debris coming out you can hook the fuel line back up to the rail and see if it will fire. Nothing wrong with going this direction but in my experience you are asking for trouble long term if you don't go ahead and replace at minimum the injectors and regulator..and possibly the pump too. If you end up taking it apart to do the injectors you might want to consider changing the EGR valve too since it's right there. At least your car has been stored indoors in a heated garage, that will help a lot but fuel system components don't like sitting.

You might want to invest in a fuel pressure gauge if you don't already have one. Either install one permanently on the fuel rail or get one that you can hook up when needed. Makes trouble shooting way easier when you can see your fuel pressure at the rail.

There are some old tech articles about changing injectors and adding a fuel pressure gauge that might be helpful to you.
https://www.thirdgen.org/technical-articles/

Hope this info helps...good luck and keep us posted!

 

On a TPI equipped F-body, you can power the fuel pump for as long as you like through the Assembly Line Dianostic Link (ALDL). What you do is, with key off and engine off, you go to the ALDL connector under the dash. It has two rows of terminals. Bottom row, connect the far-left terminal "G", to 12 volts positive with a jumper wire of at least 12 gauge. That will power the fuel pump directly and it will continue to run until you remove the jumper wire.

Fred

 

The fuel rails are aluminum. Contamination there is likely only varnish, and not corrosion. Removing the return line from the rail is going to be of almost no benefit since all return flow is downstream of the regulator anyway. The only advantage is that the fuel will not return to the tank. After about one quart of fuel flow, the rails will be clear, and a bigger concern might be the supply and return lines, and the installed filter.

Despite all the irrational fears of ethanol in fuel, it can be a significant advantage in a situation like this. Frankly, methanol would be even better at cleaning, but also risks damage to the injectors, pump, and fittings, so stick with ethanol.

 

I appreciate your comments on the TPI system. The tank was removed and cleaned with a new fuel pump, and the gas filter changed. My current plan is to disconnect the flex lines in the engine bay and jumper the supply to the return. Than I will fill tank with a few gallons of gas and injector cleaner and pump from tank through the supply to front, back to the return before it goes back into tank and use a 1 gallon glass jug to collect the fuel to inspect it and run through until clean. After that I will try connecting the lines back up in engine bay and see if I can get any fresh fuel through the rails and by the back pressure regulator back to the jug. As already stated by some here, it's a flip of the coin if the injectors will even open, but I will try this first as the simplest way. If car doesn't start obviously will be taking everything apart, if it runs, not sure what the plan is until I see how good or bad it runs.

I think EFI systems don't have as many problems as carbureted engines do because there isn't really an easy way to get exposure to oxygen because it's a closed system. Ethanol is bad for vehicles in many ways that affect power and fuel mileage. Unless you've worked on a lot of motorcycles or other small engines that are vented to atmosphere and get gummed up and can get corroded carbs from sitting over a winter, you probably wouldn't know how bad ethanol is. Alcohol attracts water, and when it sits in aluminum carbs, it corrodes badly. If you question this, I can post some pictures of some old aluminum 1972 Honda carbs that the float post just corroded away. If we didn't have Ethanol in fuel, there would be a lot less fuel problems in small engine industry.