'84 c4 just quit
Thread Starter
Cruising
Joined: Mar 2016
Posts: 11
Likes: 0
'84 c4 just quit
Pulled it out of the garage yesterday. I noticed it was sluggish, and it got worse until it quit. Now it cranks, but no start.
I'm thinking fuel pump. I saw lots of posts about going with a pump from 86 and up... suggestions??
I don't have the tool to pull codes and can't drive it anywhere to pull 'em..
I'm thinking fuel pump. I saw lots of posts about going with a pump from 86 and up... suggestions??
I don't have the tool to pull codes and can't drive it anywhere to pull 'em..
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
Pulled it out of the garage yesterday. I noticed it was sluggish, and it got worse until it quit. Now it cranks, but no start.
I'm thinking fuel pump. I saw lots of posts about going with a pump from 86 and up... suggestions??
I don't have the tool to pull codes and can't drive it anywhere to pull 'em..
I'm thinking fuel pump. I saw lots of posts about going with a pump from 86 and up... suggestions??
I don't have the tool to pull codes and can't drive it anywhere to pull 'em..
Drifting
Joined: Nov 2015
Posts: 1,714
Likes: 331
Finalist 2020 C4 of the Year - Unmodified
Only need a paper clip to get the codes. 
See directions and code meanings here:
http://www.corvettebuyers.com/c4vettes/ecm.htm
See directions and code meanings here:
http://www.corvettebuyers.com/c4vettes/ecm.htm
Safety Car
Joined: Sep 2004
Posts: 3,953
Likes: 550
From: Mission Viejo CA
'84's have a really cool feature that later Corvette's don't have! 
It's easy to verify that your fuel injectors are working! Just remove your air cleaner (easy on the '84) and watch the fuel injectors while you're cranking the engine (easy!). You should have a nice even spray pattern from both injectors. If your injectors are working, you have fuel pressure. You can't do that on later engines!!
That's your first step. What do you find?
It's easy to verify that your fuel injectors are working! Just remove your air cleaner (easy on the '84) and watch the fuel injectors while you're cranking the engine (easy!). You should have a nice even spray pattern from both injectors. If your injectors are working, you have fuel pressure. You can't do that on later engines!!That's your first step. What do you find?
Thread Starter
Cruising
Joined: Mar 2016
Posts: 11
Likes: 0
'84's have a really cool feature that later Corvette's don't have! It's easy to verify that your fuel injectors are working! Just remove your air cleaner (easy on the '84) and watch the fuel injectors while you're cranking the engine (easy!). You should have a nice even spray pattern from both injectors. If your injectors are working, you have fuel pressure. You can't do that on later engines!!
That's your first step. What do you find?
It's easy to verify that your fuel injectors are working! Just remove your air cleaner (easy on the '84) and watch the fuel injectors while you're cranking the engine (easy!). You should have a nice even spray pattern from both injectors. If your injectors are working, you have fuel pressure. You can't do that on later engines!!That's your first step. What do you find?
Race Director
Joined: Aug 2007
Posts: 11,889
Likes: 8
From: Whitefish Falls Ontario
St. Jude Donor '08-'09
Melting Slicks
Joined: Dec 2009
Posts: 2,239
Likes: 290
Most GM tbi systems don't hold pressure when off like port injected systems. Cfi doesn't hold pressure when key is off.
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Thread Starter
Cruising
Joined: Mar 2016
Posts: 11
Likes: 0
If you put the key to run, without starting, do you hear the pump run for 2 seconds?? If not check the fuel pump fuse. If the fuse is good, and you have a meter, get someone to crank the motor over. check for 12v on both sides of the pump fuse. Power is supplied either through the pump relay or after you get about 5 psi of oil pressure.. If the pump runs but still no gas, could be the fuel filter.
Le Mans Master
Joined: Jul 2004
Posts: 6,228
Likes: 698
From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Any car supply has it or can get it in a day
Last edited by Cruisinfanatic; Mar 24, 2016 at 11:56 AM.
Racer
Joined: May 2015
Posts: 265
Likes: 21
From: Grand Rapids MI
No harm in upsizing the [dead] pump to 85+ TPI...as long as you're aware it won't make the car faster! The only reason you'd ever need more pump (and actually be able to put it to use) would be more airflow from a head & intake upgrade.
Some believe the stock pump can't keep up at WOT on a stock engine. I am not inclined to agree, unless they received a defective unit.
The end result--regulated fuel pressure--will be the same...for me, it would come down to cost, and whether you have future mods in mind.
Some believe the stock pump can't keep up at WOT on a stock engine. I am not inclined to agree, unless they received a defective unit.
The end result--regulated fuel pressure--will be the same...for me, it would come down to cost, and whether you have future mods in mind.
Last edited by 84Z51J; Mar 24, 2016 at 03:41 PM.
Thread Starter
Cruising
Joined: Mar 2016
Posts: 11
Likes: 0
Drifting
Joined: Mar 2015
Posts: 1,275
Likes: 165
From: Utah
I had an issue with my 84 right after upgrading my fuel pump for more flow.
I also had an issue with my fuel gauge.
What i noticed with the pump upgrade was i could start the car, it would run for a sec then quit.
And if i turned on my lights they would not turn off in the back, sat on really dim...
I ended up getting the bright idea to connect a jumper cable from the negitive on my battery, and the other end on the fuel filler.
Right away the difference was huge, so i made a ground strap, connected one end to the 10mm bolts holding the pump to the tank, and the other end to the frame.
I also noticed with this extra ground my fuel gauge will read accurately now!
The issue was that gm has a single tiny little ground that is shared with all 4 tail lights and the fuel pump.
So as a test try the jumper cable trick the next time your getting low on fuel.
Also if you do upgrade the fuel pump, it's super easy, and once you have the strainer out of the tank i found i had easy access to my tail lights!
Might not hurt to do a proactive bulb change at that point.
I also had an issue with my fuel gauge.
What i noticed with the pump upgrade was i could start the car, it would run for a sec then quit.
And if i turned on my lights they would not turn off in the back, sat on really dim...
I ended up getting the bright idea to connect a jumper cable from the negitive on my battery, and the other end on the fuel filler.
Right away the difference was huge, so i made a ground strap, connected one end to the 10mm bolts holding the pump to the tank, and the other end to the frame.
I also noticed with this extra ground my fuel gauge will read accurately now!
The issue was that gm has a single tiny little ground that is shared with all 4 tail lights and the fuel pump.
So as a test try the jumper cable trick the next time your getting low on fuel.
Also if you do upgrade the fuel pump, it's super easy, and once you have the strainer out of the tank i found i had easy access to my tail lights!
Might not hurt to do a proactive bulb change at that point.