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Wanted to get your opinions on my Vette. I inherited this car about 3 weeks ago. To my knowledge it had set for at least a year. It did not start when I got it, but a fuel pump fixed that, while we were in there we also replaced the sock and inline filter and also cleaned out several handfuls of some kind of gunk.. .pic below in case that helps.
So here's where we're at now. The car starts and runs, but has little to no power. If you drive it around very conservatively(basically pretend the gas pedal only moves an inch or two) it does OK, but when you try to give it any power at all, it stumbles badly, and in some cases, doesn't respond much at all. After I try to get on it, it runs pretty badly even if I do drive it nicely, almost like it has to "clear out" whatever I just did... Not sure if any of this makes sense, or sounds familiar?
If it helps, I checked the fuel pressure, and it's around 45PSI when you turn the key on, but drops off almost immediately when the pump stops running. Once the car starts, the pressure holds steady at ~35PSI.
To check manifold vac. first pick up a nice gauge along with some vac. tubing and "T"s.
I like to pull the FPR tube from under the RR plenum, plug a piece of rubber tubing onto the manifold fitting, insert one end of a "T", plug line from FPR into the "T", plug the gauge tubing into the 3rd prong of the "T".
Lay the gauge on the windshield and start the engine.
Did some checking today. Fuel pressure reading was erratic. When I would turn on the key(not start engine), sometimes it would hold at ~40 PSI after the pump stopped running, other times it would drop(as it previously had). In either case, pinching off the supply or return line(at gas tank) had no influence on anything. Once I started the engine, it idled pretty steady at ~35PSI.
Decided to keep the fuel pressure gage on and go for a drive. During very easy driving, it was fairly steady in the ~35 PSI range, and anytime it bogged down, the pressure would drop all the way to 10PSI. A few times it died, and when that happened, the pressure reading would drop all the way to 0(either right before and at the exact time it died).
Not sure if that helps any.... I ordered a vacuum gage and will check the manifold vacuum soon and report back.
don't know if the 88 had a "pulsator' in the fuel line by the pump.....if somethings not tight down in there, there may be some separation of line when extra pressure is required.
since you said you just had a new pump put in......just my .02
Well there you have it then...your picture is the answer to your question. Don't you think that crap could be cutting off your fuel flow and causing flow and pressure issues?
You need to drain the tank and clean that stuff out before doing ANYTHING else!!
To check manifold vac. first pick up a nice gauge along with some vac. tubing and "T"s.
I like to pull the FPR tube from under the RR plenum, plug a piece of rubber tubing onto the manifold fitting, insert one end of a "T", plug line from FPR into the "T", plug the gauge tubing into the 3rd prong of the "T".
Lay the gauge on the windshield and start the engine.
Finally got the vacuum gage. At idle, it reads ~17 in. When I rev it in park, it drops to zero then goes back up to ~17 after it starts to rev up. I went out and drove it with the vacuum and fuel pressure gages attached. Anytime it struggles, the vacuum is nearly 0 as well as the fuel pressure. Today, the fuel pressure held after the pump stops running(it has been going back and forth on whether or not it holds.. sometimes it drops to zero after the pump stops running). Not sure what's causing this inconsistency, but it seems to run like crap when I put my foot into it regardless. When I put my foot to the floor, there's absolutely no power... the engine might as well be off. And like I mentioned, this severe lack of power always coincides with zero vacuum and 0-10PSI fuel pressure.
Well there you have it then...your picture is the answer to your question. Don't you think that crap could be cutting off your fuel flow and causing flow and pressure issues?
You need to drain the tank and clean that stuff out before doing ANYTHING else!!
Originally Posted by 81c3
I would remove the tank and get it cleaned out or replaced Flush the lines. Next, new FPR, next new injectors and fuel filter again.
Thanks for the input. Quick question, and this will sound like I'm being lazy because I absolutely am. Can I clean the tank on the car, or do I have to remove it? Any specific way I clean the tank... I have some mechanical experience, but I have never messed with fuel tanks...
Pumped all the gas(pic below) out of the tank today and did my best to clean out all the crud that was in the tank. The sending unit(also see below) looks pretty rusted and all around trashed, so that will definitely have to be replaced(it showed "full" all the time so I'm not surprised it was in bad shape.)
Questions for today
1: Assuming I can get in there with my arm and clear out most(if not all) of the debris, will that suffice, or will some type of rinsing action be required? The surface of the inside of the tank looks great(appears to have a black paint or coating that's fully intact).
2: The fuel pump was just changed a couple weeks ago, should I replace it again due to all the crap in the tank, or can I just spring for a new fuel sending unit and call it good? And to that end, where's the best place to get a new sending unit? Dealer wants almost $500 dollars... I'm seeing stuff online for $80 up to $200.. not sure what's decent..
Thanks as always for all the help, you guys are awesome
Had a couple hours to kill tonight, so I decide to clean out the fuel tank manually. Luckily the hole in the tank is just big enough for me to fit my arm down into Used about 5 rolls of paper towels and even used a little 409 type cleaner, but the inside of this tank is about as clean as I'm gonna get it! Now I just need to find a decent sending unit, flush out the fuel lines and see where it goes from there.
i'd bench test that pump before I put it in.....I use one of those 6v flashlight batteries to test it....it'll run on 6v if you don't have 12v easily accessed....make sure you get a stainless sending unit.....I've had mine in 6 years and I just had it out, it still looks new......corvette central has them. blowing out your fuel lines and a new filter will be necessary......time to change the filter is when the tank's empty....a lot easier.....
Well, after ordering(and installing) a new fuel sending unit, FPR and fuel filter, I took the old C4 out for a drive and she ran AWESOME... for about 10 mins, then died No fuel pressure at all, and I'm almost sure I can hear the fuel pump running. I'm thinking maybe something between the fuel pump and sending unit? I replaced the pulsator with a piece of rubber hose, so assuming I attached it correctly I'm not really sure what to think.. maybe I put something together wrong with the FPR and it's dumping all the fuel pressure.. hard to say. I need to double check to make sure all the vacuum lines are back where they are supposed to go... but if I installed on of those in the wrong spot it wouldn't have run well for a short time...
Good news is that I now have a working fuel sending unit, and I know it can run great! Just need to figure out what I goofed up on and get her back out there.
I had the same issue with an 89 I just purchased. It had been sitting for years. All the gas lines were rusted, so I have to change them, which is a lot of work. I pulled the filter off and cut it open and you can see what is inside! All metal from the rusted fuel sender that was in the tank. Change the filter. If you can, cut it open and look inside. I bet it looks like mine or worse.
88 Vette Poor Engine Performance
No fuel pressure at all, and I'm almost sure I can hear the fuel pump running. I'm thinking maybe something between the fuel pump and sending unit? I replaced the pulsator with a piece of rubber hose, so assuming I attached it correctly I'm not really sure what to think.. maybe I put something together wrong with the FPR and it's dumping all the fuel pressure.. hard to say. I need to double check to make sure all the vacuum lines are back where they are supposed to go... but if I installed on of those in the wrong spot it wouldn't have run well for a short time...
