CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Un-Repeatable Miracle

My '88 Chevy G20 Van (5.0 liter) was running fine when I stopped using it over 4 years ago. It did suffer from worn valve stem guides, so it would smoke for a few seconds upon starting, and occasionally the O2 sensor would fritz out causing it to run rough until it regained its composure. That was its condition when I parked it in my yard over 4 years ago.

When I first tried to start it I got no combustion, but the spark was good. So I changed the fuel filter and added about 2 gallons of gasoline to the maybe 1 gallon that was left from before. To my amazement, and without too much difficulty I got lots of combustion with the throttle fully opened … and voila, a miracle … it started, and within a minute or two was absolutely humming like I had just driven it yesterday. I put a brick on the gas pedal and let it run for about 45 minutes at about 1800 rpm. The next day when I went to start it, I couldn’t get it started, and haven’t been able to for several months now, though I try several times a week. I tried pulling the new fuel filter to see if maybe it had clogged again, but there was no resistance to my blow test, so the filter was ok and after confirming the fuel pump operation, I re-installed the fuel filter.

When I try to start the engine, I seem to get varying amounts of combustion. I seem to get the most combustion when I leave it untouched for many days. It seems the longer I leave it, the better my chances of getting more combustion. I seem to get more combustion with the throttle fully open … and none if fully closed. I have pulled the engine cover and the air filter and sprayed into the throttle body gasoline, carb cleaner, and WD40.

I have noticed that with the ignition turned on, there is the sound of some kind of small motor (perhaps?) maybe to pump fuel into the throttle body ?? But the operation of whatever is causing that soft motor sound, doesn’t seem to always result in the same amount of fuel getting into the throttle. Sometimes, after cranking, when I turn the key back (though still “on”) I can actually hear fuel swishing into the throttle body. That swishing sound overpowers the “small motor” sound. Other times however, I don’t hear fuel swishing, and can only hear the small hum of the little motor.

My (probably poor) automotive instincts tell me that when I am getting no combustion, it is because it’s not getting fuel. However the fact that relatively good combustion eventually deteriorates and then disappears altogether argues that the engine has flooded. Maybe better luck after waiting many days also argues that flooding is the problem ?? However the best combustion seems to happen when I can actually see fuel fumes and fuel spray hovering above the throttle. And other times when I can’t see hear or smell any fuel … I get nothing.

I’m at a loss as to what to do. All suggestions eagerly welcomed. If somebody could explain to me what what is that little motor sound I hear when the key is turned to “on” and how it is supposed to affect fuel delivery to the throttle, that would be helpful information too. Thanks so much.

WD 40 is something I have never tried in a carb I assume. I do not know this model but assume the little motor sound is an electronic fuel pump. and if it is a carb first stab at the cat is an improperly sealing needle and seat causing to much gas to go to the engine. It could also be moisture accumulated in the gas. See how it starts with a shot of starting fluid, if good then sea foam and a prayer, and on from there.

Thanks Barkydog. It’s actually a fuel injected throttle body. What I really don’t understand is why sometimes I hear fuel swishing in after I crank, and other times I don’t hear fuel swishing in after I crank.

It could be any number of things. My first guess would be the fuel system is clogged or the fuel is contaminated with water or other crud. It may be clogging up the fuel pump inlet. To start an engine you need spark, air, and fuel, with the correct ratio, and the correct timing. First thing I’d do is check for spark at the spark plugs. If spark is ok, suggest to ask your mechanic to check the fuel pressure at the fuel rail. And go from there.

The sound you hear is most likely the fuel pump.

The fuel pump is in the tank and not the source of the small sound I am hearing, which is coming from the throttle body area. When I had the fuel filter off, the fuel pump seemed to be pumping fuel vigorously.

I want to sell the car, and I do not want to put any money in it. It has a blown out tire, and right now will not start, although it did start before. If it starts again, I think I’ll leave it running while I post my Craigslist ad !

Are you sure you have fuel?? It’s possible your pick up is bent upwards just slightly so its nit fully emearsed in fuel. Try adding more fuel and see if that helps.

Have you checked your fuel pressure? I know you said it seemed to be pumping fuel vigorously, but you still need a decent amount of pressure to run your fuel injectors. Also, if you watch your throttle body while cranking, you should see fuel pulsing out of the injectors plain as day. If you don’t see this, I would suspect a either a fuel delivery problem or a lack of “crank” communication with the PCM, more than likely the former if you sometimes can get the engine to fire.

thanks Mark. yes yes yes … fuel delivery problem. Haven’t yet checked to view the injected fuel. Is there only 1 injector into the throttle ? Might there be a secondary pump before the injector(s) which is activated with the ignition “on” ?

… also keep in mind the engine ran beautifully after having sat for four years. It’s got oil. Is there any harm in all the cranking that I’m putting the engine through. Will it burn my starter ?

There are two injectors in the throttle body, both clearly visible with the air cleaner lid removed. There is no secondary pump, just the one in the tank. The continuous cranking is not particularly good for the starter or the battery, but the damage can be minimized by not cranking the engine continuously for more than a few seconds at a time and not completely killing the battery. If you do end up draining the battery, a trickle charge is a better, gentler recovery method than a jump start.

Fuel pump is still my number one suspect, until you say something that makes me change my mind.

All the suggestions I read here are good ones. I had this same problem with my 89 Dodge van. When you look into the throttle body there should be two black caps with 2 wires each. (these are the tops of the injectors) Pull each cap off and clean the contacts that are inside. Then, take a pin and push the contacts together slightly. Put caps back on and try to start it then.

Here’s a picture of the throttle body that I found on the web. In this picture a fire damaged the right injector.
http://www.truckforum.org/forums/attachments/chevy-truck-forum/1816d1231552634-chevy-350-throttle-body-question-img_0320.jpg

The view of the fuel being injected would be obscured by tail end of the injectors (where the wires connect). The injector is facing downward. I don’t think I could actually see the spray. Am I wrong ?
The question remains, what is that little hum I hear coming from the throttle body with the ignition “on” ?

ChenChow, very good, do you think the contacts could be cleaned with this configuration ? I’m wondering if one can simply pull up on the whitish plastic pieces to uncover the injector contacts. I’m also wondering if the hum that I hear is actually coming from the injectors themselves.

OK, I just determined that the injectors, both of them, are NOT putting out any fuel at all. My view was in fact OK. I didn’t realize there was empty space between the injector nozzle and the throttle plates. My battery was quite low, so the crank was slow. I don’t know if that might affect the injector output, I wouldn’t think so, but I’m recharging my battery (at 12 amps) now.

I also was able to remove the wire connection, and saw nothing there to make me suspicious of a bad connection. After charging I’ll see if the injectors put anything out. If not maybe I’ll check the fuel filter again.
Could there be some secondary fuel filter near the throttle body that might be blocked ? Still wondering about the very soft hum with ignition on. What is that !?

Did you try adding more fuel yet??

Mark9207 is to be commended for his insistence that the fuel pump is the culprit. I was skeptical of that because when I rechecked my new fuel filter a couple of months ago, it seemed to be pumping fine. But today after discovering, thanks to Mark, that the injectors were putting out zilch, I pulled the fuel filter again. It was fine, but when I had my wife turn the key, a mere dribble and then none came out of the fuel line leading to the filter. The good news, my engine has great hope for it, it probably does not have a stuck valve.
The bad news, my van, which I want to get rid of, and don’t want to put money into, has the functionality of a backyard shed … which is in fact what I was using it for over the last few years, while I rebuilt and put a floor into my actual shed.

How much of a pain is it to replace my fuel pump ? What bloody reasoning inspires manufacturers to put a fuel pump inside the gas tank !!??

btw, gsragtop, although I had not mentioned it in previous posts, a few months ago, I added another 3 gallons of gas, which means more difficulty in replacing the fuel pump. whooppee.

Ok, try this. With the truck turned on. Try hitting the fuel tank with a hammer, a few times around the center if the tank. In some cases this will get the fuel pump spinning again.

Thanks gsragtop. That’s the kind of advice I can use ! I was wondering if the strainer might be crudded up.
Right now I’ve just showered and it’s already 90 degrees out. I’ll try it as the sun goes down…

LOL, the pump is basically a small electrical motor… If it has a bad winding and stops on that one bad spot it will not go again. HOWEVER buy hitting the tank the vibrations can get the windings to move just enoph to get off the bad spot and then the motor starts spinning again/pump starts pumping again. Let me know how it works out for you…

gsragtop, no luck with the hammer. With a rubber mallet I pounded the bejeebies out of the bottom of the tank, but got no fuel … just bejeebies. The fuel pump seems fully dead … unless it’s a fuse. Anybody know where the fuel pump fuse is on a '88 G20 Van ?

I think it’s under the dash, but I’m not sure.