For reasons unrelated to vehicle issues, my 1987 C4 (108,000 miles, original owner, bought new) sat idle for about a year – with very little gas in the tank. I want to rectify the situation now and would seek guidance of sorts on checking lines, injectors, etc. Mostly, cautions on what to do and what not to do. I'm a reasonably competent car guy but looking for guidance from more knowledgeable minds than mine.

First thing is the tank itself has rust sediment in it, particularly in the plastic...(what's it called?)... that the fuel pump sits in. I'm cleaning that and the tank itself out and plan to use vinegar to dissolve it, then thoroughly clean it out. Will the vinegar (or other product) harm the plastic...sleeve? Once that's done, can I just check lines and pressure at the Schrader valve – or somewhere else along the way? Fuel pressure regulator? Fuel rail?. And since the fuel injectors are the originals, it seems like a good idea to replace them.

 

Why vinegar? Not sure how comfortable you feel with vinegar residue in the tank. Some people don't want that even so, your call?

Not sure how to check all those items you want. If I were there already, I'd just get a Racetronix kit and install it to remove one variable. After which, change regulator and as far as injectors, if they are not Multecs, send it to FIC for checking. If they are, throw them away and get rebuilt ones from FIC

 

If there is rust sediments in tank you need a tank the rust isn't going away. Figure on replacing pump and sender no need to put old parts in a new tank. Replace fuel filter also. Injectors could be gummed up depending on quality of old fuel, you really won't know until you try to start it. Use hand vacuum pump to make sure FPR diaphragm is good, don't apply more than 20 inches of vacuum.

 

Thanks for the replies. As for the “rust”. That was based on my initial visual look down into the tank and – with very little gas in it – an observation of what looked like some thin sediment or something. After reading your comment(s), I just went and wiped the surface with my bare hand and, whatever it is doesn't even show up on my fingers as anything other than liquid. So I don't know that it's rust at all. There was sediment in what I now know is called the sump but that's all cleaned out. And, btw, the liquid smells like gas. I have smelt bad gas before and so maybe I don't have as big a chore as I thought.

I am replacing the pump and sending unit and fuel filter and will see if it starts and how it runs. (Ran quite well before all of this so...) Will work my way forward as needed and see what's what.

Thank you again.

 

I would fill the tank with water and drain it out a couple times to get any junk out of the fuel tank. I used a shop vac to empty the water and dry out the insides before I put gasoline in it. I would use a siphon hose if the first mixture smells of gasoline. I used a mild de-greaser to help clean the tank out and rinsed it well afterwards. The de-greaser helped eliminate the fumes and cleaned the tank for me.

Having left a C4 for a while I too suffered from "grungy tank syndrome". The worse part was that my fuel supply line nearly rusted shut and that is a real PIA to fix properly. I could get the right fuel pressure but insufficient volume to let the Corvette to run properly. Not an easy thing to diagnose...

Today's gasoline with ethanol in it acts like brake fluid and it absorbs moisture the same way. If you leave modern (Oxygenated) gasoline for more than 30 days it starts going bad. With the gas and water sitting in your tank there is a likelihood of rust somewhere in the system. Never leave oxygenated gasoline in your Corvette for 30 days without adding a fuel stabilizer.

If your Corvette has been using Ethanol for a while it would be a good idea to check the Fuel Pressure regulator's diaphragm, they were not made for oxygenated fuels. If you haven't changed it you might want to add that to your list.

When was the last time you flushed the brake fluid out? That needs to be done on a schedule like every 5 years. After my car was fixed and running I stepped hard on the brake pedal and a brake line blew out. Again, corrosion on the brake lines.

The original injectors were not designed for oxygenated fuels and they do break down. There are several places to get injectors but most of the folks here on the Corvette Forum buy them from FIC or South Bay Injector. I have purchased several injectors sets from South Bay Injectors and have been very satisfied with their services.

After the fuel system is clean try a can of B&G 44K Fuel Injection System Cleaner as it will help finish the job and clean out the lines and other parts. I use 44K whenever I feel a "miss" in one of my vehicles. I TRUST B&G products, they are not "Snake Oil" as some will lead you to believe.

 

Make sure the fuel rail holds pressure before you crank it. I bought my '90 with a rod through the pan because it hydro-locked from two stuck open injectors after sitting.

 

You sure? I thought it was 3 months before you need to put a stabilizer in it?

IF you are going that far, I really don't see what there is to do as far as checking. Might as well put a new one in, assuming they are made new enough to be ethanol resistant. At this point, might as well toss the injectors if they are Multecs or send them for cleaning and testing since they probably have varnish in them. Even regular use cars build up varnish after a few years.

I believe MB uses 2 years as a standard. I heard of a *** car recommending 3 but not sure which one.

RC Engineering is another one that might work.

Soon as they publish a test where we can critique the methodology and stop relying on subjective testimonials, I'll trust them. Till then, it is a matter of "believe".

 

Thanks very much. Valuable information which I will certainly absorb and follow.

 

Oooh! Thanks for that info.