1988 Chevy c3500, injector spray dies out when throttle is pressed

10

Asked by Itwontdiebutitwontru... Mar 08, 2019 at 12:35 AM about the 1988 Chevrolet C/K 3500 Silverado LB RWD

Question type: Maintenance & Repair

Hello. So I have a 1988 tbi 350, I started
having this problem months ago to where
when I pressed the throttle to wot, it would
lose power and fall on it's face, it
progressively got worse, it started
happening at 3/4 throttle and up, then half,
an now if I press the pedal at all it dies. I
watched the injectors while hitting the
throttle and at idle they are perfect, but when
I touch the throttle any the cone spray turns
into a smaller and smaller cone the more the
throttle is open, it is causing the engine to
lean out and die. I have replaced the sending
unit and pump, and tested pressure and
current and they are good, I have replaced
the tps, aic, distributor, cap rotor and wires
are all new along with ignition control
module, coil, coolant temp sensors (both)
and re built the tbi unit completely (with a
new regulator spring). Nothing has helped.
The only things left to replace would be the
injectors, the ecm, and the knock sensor. It
is throwing no codes at all. The egr is
deleted, and has been for a few years now
with no issues. What is your opinion?

19 Answers

10

I will check it in the am, but it is new, I thought that was my problem at first so I replaced it with a new one, it still acted up so I swapped it with one from my other truck that runs perfect an still no help

10

No mass air flow sensor, it seems to me that something is causing the injectors to shut down when the throttle is pressed, if they were plugged, wouldn't it idle funny too, and not spray correctly? I've checked them under the timing light and there is no difference between them and the ones on my other truck at idle.

2,570

Sounds more like the computer cant determine proper fuel delivery or you have some kind of fuel volume loss, such as reatrictions or bad power/ground maybe.. when you tested amperage what reading u come up with

10

When I tested the pressure it was idling at about 11 psi or so, but it will idle fine for a bit then get choppy, sometimes die. I have to feather the throttle to keep it going for the most part, it will try to die when I hit it but as soon as I let off it jumps back up in idle. I will get random backfires depending on how fast I pump the accelerator to keep it running, and it doesn't seem to run much higher than 1200-1500 rpms. The symptoms are that of a bad fuel pump, but everything on that end checks out and is brand new.

2,570

Thats good amperage, what id do is make sure your map sensor is getting a proper power/ground.. it doesnt surge or anything does it

10

It does, it will run fine for a minute maybe, surge for a few seconds, sometimes enough to stall, and sometimes it picks back up. If I understand plug it, it will idle higher, but still do the same thing.

10

I know, lol. It leans out severely when I hit the throttle, I just don't know what would cause the injectors to basically close up when I do, besides the ecm, at this point. I guess I'll have to wait and see, if it's not that then I don't know what else it could be, the probability of both injectors doing the same exact thing at he same time seems a little odd, as far as having them both go bad at the same time the same exact way

2,570

Well if u had a way to scope the injector you could see of your losing injector pulse... id unhook your battery and let it set long enough to wipe all the learned memory out of the computer and see if it still does it

10

I've tried that, I've had the ecm completely out, when it's cold and I start it, it idles perfect, no problem, when the choke shuts off it acts up, but I can't hit the gas or it bogs down.

10

Update, I replaced the computer and Injectors,still not any better, it idles perfect now, but as soon as I hit the gas it wants to lean out and die. New fuel pump, sending unit,filter, plugs, cap, rotor, distributor, Icm, tps, iac, coil pack, computer, injectors, egr delete for quite some time, tbi rebuild with new regulator spring. There is nothing left to replace, no codes.. still looking for suggestions.

10

Still looking for help. I've been tracing wires and haven't found any bad ones, grounds are all good. Any advice?

1 people found this helpful.

Your Answer:

C/K 3500

Looking for a Used C/K 3500 in your area?

CarGurus has 1 nationwide C/K 3500 listings and the tools to find you a great deal.

Postal Code:

CarGurus Experts

  • #1
    Joe_2019
    Reputation
    400
  • #2
    Gene Arnett
    Reputation
    380
  • #3
    Keith Massey
    Reputation
    220
View All

Find great deals from top-rated dealers

Search

Related Models For Sale

Used Ford F-150
363 Great Deals out of 12,802 listings starting at $599

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use. Content will be removed if CarGurus becomes aware that it violates our policies.