thunderstruck507

iTrader: (18)

On 2 separate occasions now my car has had an odd fuel starvation type issue.

(both time have been after long drives in 90* heat)

The first time was last year and it died and would not start until I walked looking for a parts store and came back then it fired right off but wouldn't rev over 4000rpm. As soon as I got it started I stopped and topped off the tank along with some HEET additive thinking I had some bad fuel. Changed the fuel filter the next day and thought it was settled.




Friday I drove the car to the track. It cooled down long enough for me to empty the trunk, uncap the exhaust, lower tire pressure, and fill out tech cards and stuff.

First 2 passes it did the same thing, hit a wall at 4k rpm. On the second pass I even let out then rolled back into it in 2nd gear and it still did that above 4k.

Immediately turned off the track and went straight to the gas station, topped off the tank, and it never acted up again. It only took 6 gallons to top it off to the brim though.





I am running a stock tank with a box welded around the pickup for some fuel control, a Mustang GT inline filter, Corvette regulator/filter, Walbro external pump, all new steel fuel line.

The car was only cutting a 1.78 60ft and had 14 gallons, so I seriously doubt it was a pickup starvation issue. It's never been a problem before until I was down to 5 gallons.




Does it sound like I'm having an issue with the fuel system overheating? All the above parts are mounted above the axle. I am not sure what else the problem could be. It's very rare making it hard to diagnose.

Any other theories?

thunderstruck507

iTrader: (18)

I'm kinda thinking a vented gas cap might prevent this in the future

bigchief52780

iTrader: (10)

if you want a tank for efi go to amazon.com. i ordered one for a 70 cutlass and paid $233 for it. it was priced at $821. it is showing $383 right now. the link is below.

bczee

iTrader: (12)

get a pressure gage on and watch it as you get it to WOT.. also get the scanner on and log review the logs as it happens.

Do you have a EVAP system ?.. or at least a Vent with Charcoal Canister ?

Heat.?. Vapor Lock problems ?... how hot is the fuel rail when this happens. I would not thing it would be a problem if you have a return line system.

Been a while since I read what your car has..

BC

thunderstruck507

iTrader: (18)

my car has the fbody rail from a 98, the return line comes right off the Corvette regulator above the axle and feed back into the tank

I do not recall how the stock tank vents are currently hooked up but there is no charcoal canister I'm aware of, I will have to crawl under there and tank a look...I think there is a vent issue sometimes when I open the cap I hear pressure and sometimes not

the fuel feed come from the stock pickup into a filter, to pump, to corvette regulator/filter, to fuel rail

bczee

iTrader: (12)

Ok. if your hearing air escape or being sucked in.. sound like it is a venting issue.. I would key in on the Venting..

The stock A-Body tank should vent (2 or 3 vent lines from the tank) into a Seperator unit that is on the body behind the Rear seat.. then routed to a Charcoal Canister in the front. See how much of it is still being used.

Could be the vent line is old and not collapsing and not venting anymore ??

let us know what you find !
BC

ls1nova71

iTrader: (4)

Where is the Mustang GT filter? Are you using it for a pre filter for your pump? Might be too restrictive?

thunderstruck507

iTrader: (18)

the Mustang GT filter is a pre filter for the pump...just didn't like the idea of unfiltered fuel going to the pump, it has been set up this way for several years and many thousands of miles, it did get clogged once and I have changed it a few other times

also prevents ruining the more expensive Corvette filter as often



I am fairly certain I hooked the hoses back up to the separator unit but not sure where it goes past that. It is also possible the hose collapsed as you said. I was going to look last night but I spent nearly 2 hours working on other stuff in the garage yesterday and got too hot so I called it a day early. I'll get it in the air and see what I have. I agree with you I really think it's a vent issue more than anything.

Lonnies Performance

iTrader: (16)

I would get rid of the pre-filter. Once the fuel gets hot from driving, the pump will cavitate as it draws against the restriction of the filter. The only pre-filter you should run is a stainless mesh type.

rockytopper

Yea I never really got the pre filter thing. The in tank pumps are sucking the same fuel as an external. A standard oem sending unit has about the same sock as an internal pump does it not? Or am I missing something? I've got about 36 k on the same setup less pre filter so lets say I'm a test in progress.

Pop N Wood

iTrader: (1)

+1

Summit sells a pretty cheap in line prefilter, although I'm not sure how you would mount it in the tank. 40 micron is good for the gerotor pumps while you can use 100 micron with rotary vane pumps. cheap insurance to protect your pump from locking up on tank debris. But like Lonnie says it needs to be super low pressure drop. With less gas in the tank there is a lower static pressure at the pump making it more likely to cavitate.

http://www.summitracing.com/parts/sum-230105/overview/

ls1nova71

iTrader: (4)

http://www.robbmcperformance.com/products/filters.html
This is what I'm using. Cheap and made in the USA. Can't beat $27. The reason I asked about the pre filter is I had problems trying to use a regular filte. The RobbMC one works great.

thunderstruck507

iTrader: (18)

I was using the pre filter because there for a while around here it seemed like a lot of dirty gas was being delivered and I didn't want to be replacing the corvette regulator/filter all the time.

Guess I'll look into the vent issue and go from there, possibly ditch the prefilter