Camaro keeps dying going down the road!

[cw67]

I can drive the car 10 miles or so before it starts acting up. It acts like it is running out of gas, but will shut down pretty quick. It usually cranks back up with not much of a problem. It then may not do it again for another 10 or 20 miles. I cleaned the bowls out in the carb, thinking it was just dirty, but that didn't help. I have a glass clear filter right out of the mech. pump. I would think if it were the pump, that it would just work or not work. I also thought it could be electrical problems. Would a coil going out do this? I have a Mallory unilite system with a promaster coil and hyfire box. I have had this system for at least 10 yrs. w/ no problems. Any sugestions would be greatly appreiciated.

Thanks
Chris :confused:

[MrQuick]

10 years on a Unilite?? You are a first...have you had, any shorted out or grounded secondary wires lately?

With out checking it and getting more info, my swag would be the unilite module (led pickup). IME: Hyfire boxes go out and stay out. What does it sound like before it dies? Make a suck sound the stumble or a clean shut off?

[cw67]

I did recently put in a new stereo system, but it was doing it before that. I really just need to put in a new updated fuse block and redo the whole system. The more I think about it, it could be a fuel problem. When it dies it really doesn't spit a sputter unless I floor it. I think the front primarys on the carb is not getting fuel but the rear ones are, because when I punch it I can hear it bogging down. Can the needle and seat be going bad? Can the front primary pump diafram make it do this? It is just weird that it only does this sometimes, other times it runs great. I have a holly 650 double pumper mech. carb. w/ a mech. pump. The pump has been on there for at least 10-12 yrs. Thanks in advance for any suggestions.

chris

[Matt@RFR]

It wouldn't start right back up if it were a bowl going dry.

[TonyL]

is the gas tank vented?

try driving it with the cap off. Sounds like starvation.

[dgumoe]

vapor lock maybe?

[CAMAROBOY69]

I have had this happen on 2 vehicles. It was the fuel pump on both of them.

[cw67]

Late last summer on my way to a car show it did this and I had to work on it on the side of the interstate in 95° weather. (NOT FUN!)The front bowl was completely dry and I was only getting gas to the secondaries. After cleaning the needle and seat and looking for a cup in the ditch to put gas in to prime the carb, I was able to get it working again. I drove it another 80 miles or so with no problems. I thought after cleaning the carb up some that I would have fixed it, but it keeps happening. It has a stock tank in it, I don't think it has a vent. I thought of vapor lock, but i don't think that is it. CAMAROBOY69- does this sound like what your 2 vehicles were doing? Thanks for the help guys!

chris

[CAMAROBOY69]

My 2 vehicles did the same thing. They would drive a few miles then just die. I let them sit, restart them then go again. If I wanted them to die within 2 miles I just floored it. If I got on them they would both die quite quickly. THe fuel pump was a guess on both vehicles and it was the same thing. I guess it was a good guess. ONe was a chevy fuel pump $7.00 the other was an Oldsmobile fuel pump $20.00. Everything on my olds was more expensive. everything.

[cw67]

Thanks everyone! I think I will start the process of illimination and buy a fuel pump.

chris

[paul67]

can you check the fuel pressure

[cad]

Same thing on my mechanical pump....try a new one, or measure fuel pressure while driving.

[cw67]

I don't have a fuel pressure gauge on it. I will probably add one when I change the pump. Any suggestions on pump. I was looking at the summit 110 gph pump. The motor is pushing about 400 hp.

thanks, Chris

[Madspeed]

I would suggest that you check the fuel line from the top of the tank to the line first.
I had a customers 66 chevelle do the same thing and nobody could figure it out.

I checked the line and it was old and soft so it would suck shut when the exaust heated it up and sofened it more.

replaced the line and she runs perfect again.


( no the fuel line isnt that close to the exaust but heat dissapates pretty far from itself)



hope this helps gl Ken F

[paulk68]

Sounds just like my 91 camaro problem. It was the fuel Pump. like camaro boy said i could drive it for a little while then it would die after sitting for 5-10 minutes it would start again and get me another couple miles. what pain to drop the tank and switch it but that is what it was.

[Bclarke]

I am having this same type of problem. I thought it was heat / vapor lock issue at first, so I swapped out the electric pump and re-routed some lines .

I can touch the fuel lines with my bare hands and they are cool.

Loose pressure after about 5 minutes or so, Starts at 6-7 psi , then drops to 5, 4, then 0.

Stock fuel Tank (brand new)
Stock Sending unit (3/8th feed line, new)
-6 AN Fuel lines, (new)
Holley 80gph mech. pump (new)
Demon 650 (new)

No leaks, good vent on tank/cap

I'm stumped

[chicane67]

10 years on a Unilite?? You are a first...have you had, any shorted out or grounded secondary wires lately?

One thing about a Uni-lite....... it either works or it doesnt. I would look into the pump myself.... first.

[Madspeed]

have youo pulled the sender unit out of the tank?
if it has the factory sock on it they tend to glogg up remove it and clean the tank out

another easy test would be to run a hose from the fuel supply line near the tank into a gas can and see how long it runs
keep a fire ext nearby

[OHCbird]

I agree w/ Madspeed on both of his points- I've seen the factory lines collapse internally, choking the fuel supply. Ditto on the sock- while it may still flow some fuel, it acts as a restriction, which exacerbates the fuel line collapse.

[Bclarke]

Thanks for the tips.

I have not pulled the sender out, I just put the Tank and Sender in. The Sending Unit 3/8th line is steel.
They are both brand new. I suppose the sock could be clogged or sucking in the tube.
What gets me is it has good pressure to start , then fails over time.

I like the idea of running from a 5 gallon can to eliminate the tank / sending unit, I am going to try that.

When I pulled the electric pump out to try the mech. fuel was flowing out of the feed line like crazy (siphon effect), so I don't think anything in the tank to pump part of the system is clogged.

I think I may pull the fuel filter out of the system tommrow too, its an Earls -6 inline .

[Madspeed]

The fuel may pour out like a river but under a vac it will collapse a rubber hose (that is weak) or pull crap up to and clogg the sock
when the engine dies the fule drains back out of the line and cleans the sock.
Another possabillity is the fuel filter is clogging as well. The same princaple when fuel flowes through it to the carb. The junk in the line collects in the element untill its clogged then when the engine dies fuel flows backwards to the tank again unclogging it.

EDIT Hmm I would go for something old first rather than a new tank or sender unit (event thought its a posabillty)
Check the fuel filter first I gaurentee you have a clogg of some kind and id doubt you have vapor lock unless you have a line touching something hot like the waterpump or heater hose.

[Bclarke]

Thanks Mad,

Everything is brand new from the tank to the carb. I was going down the vapor lock trail on the first drive a couple days ago, but I can duplicate the issue in few minutes now, the lines are still cool to the touch. I did re-route a tranny cooler line that was touching the fuel line.

I am hoping / thinking something is clogging at this point. I don't have any rubber hoses, all steel or braided AN type.

I have not touched the Demon yet, as I am not very comfortable with the internals of a carb, but I guess it could be clogging too?

I'll update after more diags.

The good news is the short distance I made it away from the house on the first drive it was running great, chirpin the tires on every shift :)

[Bclarke]

quick update.
Ran it from a Gas Can - -6AN line to Pump - -6AN to Carb, no loss of pressure bounces from 5.5-6psi but does not drop off all together !

Now that means its either the Filter I have in front of the pump or the Sock on the pickup tube right ?

I hope its the filter, cuz I don't want to have drain / pull that gas tank again, I just replaced all that because of a leak in the top of tank.

[Bclarke]

another update, pulled the fuel filter (Earls) I think I may have re-installed it backward not sure yet, but was real dirty / slimy.

I wonder if the inside of the new tank needed to be cleaned before use or something? You know how new metal has a coating of oil on it? It is a Goodmark Tank I ordered from summit.