Hey guys, recently my truck has been acting up on me.. It acts like it stops giving it enough gas, then it will come back and be fine. This has been happening since i changed my oil (to a synthetic blend for the first time) and air filter about a week ago. Funny how these things always happen after you do something, eh?
But i dont think that its related.
Most of the time it seems like the truck has to "warm up", but tonite its been doing it a bit more than usual.. When i'm sitting at idle, it will all the sudden start dieing, and i have to rev it to get it to stay going.. Then, while going down the road, the only way i can describe it is it feels like a massive misfire.. I have to stomp the clutch to keep the tranny from blowing apart it feels (and sounds like)... its a violent misfire, is the best way to describe it. I thought that at first it was just my rear fuel pump finally biting the dust, since thats been iffy for a while now, but it does it on the front tank too.. I've been thinking one of 2 things.. fuel pump relay, or fuel filter.. but i cant picture a filter making that drastic of an effect, and i dont know at all about relays, other than that mine have been messed with by a previous owner, by the looks. I dont know where else to look, so any ideas would be good.. thanks in advance

-Dave

 

Get a fuel pressure gauge & look in the EFI Fuel Pump album in my signature link. Read this thread about the relays.

 

you may have bumped a vacuum hose or a electrical connection while you were servicing it. check all vacuum hoses and wire connections. with wiggle test. also check to see if there are any codes stored.



Bruce

 

I think i've narrowed down the problem.. I wiggled both the "Fuel Pump" and "EEC Power" relays, and when i wiggled the EEC one, it went from almost dieing, to running fine, then i let go, and it started dieing again. I took it off and the metal contacts looked a little corroded, but not bad, but i cleaned them and put it back, and it does the same thing.. so does this sound like a problem that could be caused by a bad EEC Relay? What exactly does the EEC relay even do? i have no idea about the electrical stuff on this truck.. any more help's appreciated! Oh yeah, and i changed the fuel filter too, but it didnt do anything....

-David

 

When the key is turned to on, the EEC relay is triggered to send power to the main computer to turn on. Then the computer triggers the fuel pump relay to send power to the fuel pump.

The stock two relays are known to crap out and a good idea to replace with a standard bosch style 4 (or 5, it don't matter) pin relay. Napa has em for a good price along with the handy pigtails.



Part numbers AR272 and EC23.

My two on the 88 are going bad (need to give a wack sometimes) and I'll get around to swappin' here soon.



Careful though, these relays get addictive to use



Adrianspeeder

 

Hey, thank you for your replies so far... The more that i think about this thing, the more mind boggling it gets. Okay, one of the relays had been replaced.. the fuel pump one, with a yellow colored universal looking one. The EEC one's original, and the old fuel pump one was still up under that little plastic box, unused. Its weird how this problem happens.. it'll be fine for like 12 or 13 miles of driving (luckily thats the distance to and from school), then it starts sputtering and trying to die. I got pissed and did some swapping around when i got home today, and plugged the old fuel pump relay in, and put the yellow universalish one on the EEC plugin, with the old EEC one off. This made the truck idle without dieing, but a little test drive proved that this was worse, it was like trying to push it past 1100 rpms was useless, it'd just loose power, so i got it back home and tried to rev the engine a little, and it would hit 2000 rpms, and not want to go any higher. So i undid the relays and put them back to the way they were, and now its doing the same thing (not going past 2000 rpms without sounding like $h1T, i didnt dare test drive it) !! And the Check Engine lights on!!!! what is wrong with this thing, i'm so lost right now, and my chevy loving buddies arent going easy on me

.....I plan on finding how to check for codes now, i'll post what i find in a little while

-Dave

 

I'm still lost about this truck, i gave up on trying to get codes pulled, i thought that it was simpler than what i read.. Anyway, i think i uncovered another problem while i was digging around my engine compartment..lol.. i figured i'd check my plugs, make sure they were all snug, since my #6 one has a tendency to loosen up on me, and that one was loose, but tightening it didnt fix the problem, as i knew it wouldnt. when i got to the #3 cylinder, the wire basically broke apart in my hand. the metal that connects to the plug ripped out of the end, and it didnt take much force either. and i could wiggle the plug a bit with it screwed in! so, i'm gonna buy new wires tomorrow, and i still dont know about the relays, since i dont know if the relays would cause the problem to happen every so often, i'd think that a relay either works or it doesnt.. but i dunno.. i'll stop rambling for now..lol...

-David

 

i hear ya dude! i am chasing my tail on this one too, (i kinda have the same problem)when these relays crap out do the fuel pumps come on at all or just real weak?? my pumps make noise and all, but could it be they arnt getting enough juice to the pump? or not a steady flow of power? oh and if you buy a fuel pressure gauge i would not get the one from harbor freight. mine leaks from inside the gauge itself, and not a drip drip either, like soak your shoe if you aint payin attention kind of a leak whos up for a 4bbl holley swap!

 

This truck is still doing this to me.. and its not the relays. I replaced those the other day, and it does the same exact thing. I'm really getting annoyed about this.. I've gotten two more ideas as to what it might be, but i'm hesitant to throw money at this thing to try to get it fixed when i dont really know what it is. What i've been recommended is #1. Coil. #2. Something that goes under the distributor that has a grey plugin going into it (i forgot the name). I'm suspecting the coil is bad, because for about 3 days before it started acting up, my tach acted funny, jumping all over the place, and now when i know its going to mess up, the tach does that a lot, then goes down to 0, then the truck dies. I dont know about the "under the distributor thing", one of my buddies mentioned that..
But this is starting to really make me crazy. I dont really feel like going junkyard searching without knowing what to get yet.. so feel free to throw out anymore thoughts/opinions.. And a 4bbl holley swap is sounding like such a good idea right now.. electronics complicate everything.

-David

 

If you get a Haynes manual & a cheap multimeter, you can test the whole ignition system in less than an hour, and then you'll KNOW if the coil, TFI, or PIP is the problem.

 

My '89 is doing the same thing as David's,what with the tach needle jumping up and down.I don't mean slowly moving up and down but jumping all over the place then the truck dies.Where does the tach get its signal from?The ignition coil?I think wherever the tachs signal comes from is the culprit.

 

Then TEST it.

 

Hey Billy and everyone else.. i figured out what was the problem.. I replaced the coil first, which is where the tach gets its 'signal' from, but it kept doing the same thing. The next thing i replaced was the TFI module, or distributor control module as they call it at carquest (cost like $40). This is what solved the problem. the trucks been running like new since i put in the new one. I think that if i had replaced that to begin with, i wouldnt have needed the coil.. but i'm sure it didnt hurt. And yes.. if you have the patience and tools.. do what Steve says.. and test everything. It would've saved a little bit of money.. but i do things the old fashioned way. :o

-Dave

 

something else i figured i'd add.. i'm sure that when the TFI module dies, its probably different symptoms for everyone.. but for me when it first started happening it wasnt to bad.. it wouldnt kill the truck completely it would just cut out for a split second then come back. it did this driving down the road and idling. At first it wouldnt even kill the truck when it would idle.. it would just about die then surge back to normal and be fine for a while.
The amount of time that it would run normal started to decrease little by little as time went on. Right before i replaced the module it would only run for about 1 minute and a half before it started acting up. I figured i'd go into some detail just to help ya figure it out. Hopefully you get whatever's ailing it fixed soon.. not having your truck going sucks.. believe me I know....

-Dave

 

Thanks david for a good description of what you're truck was doing and the solution.Mine was doing the same thing.I replaced that ignition control module and its running fine now.