Re-tuning for warmer weather?

["Turbo-T"]

How does a pump that pushes fuel have to work harder on a higher boosted engine?

 

[TurboBuRick]

Because it has to meet boost pound for pound. The more boost you run , the more fuel pressure that is demanded.

 

["Turbo-T"]

Ok. Just I was under the impression the pump just flowed fuel up to the injectors and the regulator is what pressurized all of the fuel. Unless if you mean there's not enough fuel coming back to the pump in the return line.

 

[TurboBuRick]

I know it's confusing.

Basically the regulator restricts the return fuel resulting in more fuel pressure. The more return fuel restricted = more fuel pressure = more load on the pump.

Ultimately the pump is what has to make the pressure.

 

[Nasty]

The regulator restricts the fuel increasing the pressure. This resistance makes the pump work harder. The hard a pump has to work, the shorter its live. I have a Racetronics unit, hope it does not fail. I just read a thread about the Accufab regulator causing a problem like the original poster is having. It had something to do with the washer/nut setup on the regulator allowing boost to drop off. It tells you what to get from the local hardware store to correct it. I would perform that mod before buying a pump. Even if it does not fix the problem, it would only be a couple of dollars at most easy to perform. You would at least be assured it would not be a problem in the future.

 

[Quik Six]

My first suspect would be the 1/4 tank of gas. I will not hammer on my car with anything less than 1/2 tank since it moves around a lot under acceleration.

My car doesn't like hot weather so I just lower the timing and run it a little rich in the summers and play with it in the mornings.

 

[84BuickGNYorkPA]

Some guys replace the fuel pump every year, cheap insurance, I wait untill I see your symptoms, lower then normal pressure in boost. I bought my last one at racetronix and added a extra ground wire, so far so good.

Chuck

 

["Turbo-T"]

I see now. The fuel flow obviously is one way but excessive pressure causes a resistance on the pump itself. Going against the flow. Thanks for the clarification.

So I take it, for running high boost, it's the norm to have to replace fuel pumps? Or is there one on the market that's set up to endure the amount of boost I'm running?

 

[garyk1970]

My first suspect would be the 1/4 tank of gas. I will not hammer on my car with anything less than 1/2 tank since it moves around a lot under acceleration.

My car doesn't like hot weather so I just lower the timing and run it a little rich in the summers and play with it in the mornings.

Bingo.......a submerged pump will stay cool and perform bettter....put some fuel in the tank first...

 

[Quik Six]

I see now. The fuel flow obviously is one way but excessive pressure causes a resistance on the pump itself. Going against the flow. Thanks for the clarification.

So I take it, for running high boost, it's the norm to have to replace fuel pumps? Or is there one on the market that's set up to endure the amount of boost I'm running?

The answer to your question is in these charts. Tried to email you a calculator version of this but it was rejected as too large.

Performance, Horsepower, Injector, Fuel, and Turbo Guide

I just reread your parts buildup. You're running 38# injectors with a 60 turbo at 25#'s of boost. You probably need 50's or better at those levels.

 

["Turbo-T"]

Bingo.......a submerged pump will stay cool and perform bettter....put some fuel in the tank first...

So you think I should just try this before dropping the tank and spending $130 + on a fuel pump?

The answer to your question is in these charts.

I just reread your parts buildup. You're running 38# injectors with a 60 turbo at 25#'s of boost. You probably need 50's or better at those levels.

I've asked about my injectors in the past and have gotten mixed replies, but most said to "stick with what you've got". FWIW I've only gone a best of 12.61 @ 109 mph with a poor 2.00 60 ft. due to bogging at launch. So there's definitely more potential.

I looked at the chart you posted....correct me if I'm reading it wrong but are the rows of numbers below the duty cycle numbers, the size injector required for that trap time/1/4 mile time? Also are most TR's ran on an 80% duty cycle?

 

[Quik Six]

Reading across the line for 12.43 time, the chart says that 38# injectors will put you in the mid 80's for IDC and that is good. Most say to use 80% IDC to size you injectors for your combo. Your IDC was better than I expected but I also expected to see different times. Moving down to the 11.78 line, you would be running the injectors at 100%+ and the misting benefit of the injector would be minimized.

I think your fuel level was low enough to the pump could have been pulling in some air along with the fuel and that is what caused the knock. Just go out and try to empty the tank with the fuel pump and a hose; if you don't get a steady stream of fuel, turn off the pump and add a few gallons of fuel and then try it again. If it works fine then you were running out of fuel, if it continues to surge then your pump is probably shot. Your timing may be too much for the weather so if you can take out a couple of degrees, I'd do that. If you can't do that, I'd either drop the boost a pound or two or slightly increase the alky.

Good luck.

 

[bmackinnon]

I think your fuel level was low enough to the pump could have been pulling in some air along with the fuel and that is what caused the knock. Just go out and try to empty the tank with the fuel pump and a hose; if you don't get a steady stream of fuel, turn off the pump and add a few gallons of fuel and then try it again. If it works fine then you were running out of fuel, if it continues to surge then your pump is probably shot. Your timing may be too much for the weather so if you can take out a couple of degrees, I'd do that. If you can't do that, I'd either drop the boost a pound or two or slightly increase the alky.

Good luck.

This is baloney... and you know it... True, it's not a great idea to romp on it with less than 1/4 tank of gas, but i've done it MANY times with 1/8 or so and never seen my hood mtd gage quiver... but, like Gary said,... prove it to yourself by putting some more gas in it, find some open road, do a gentle 3rd gear roll so as to build the boost gently, whilst not sloshing the fuel too bad since you're in 3rd and not violently accelerating....all the while watching the fp gage.... you will find the same result... fp rises up to a point, and then starts dropping... = dead pump.... sheesh... (rolleyes not towards you O.P. :wink

 

[Quik Six]

It's not baloney for a modified car and you are assuming that his 20+ year old fuel gauge is correct.

We have a few guys in our club that run 60 turbos and they are mid 11 second cars. I expected that his numbers would be similar.

 

[Grumpy]

I've asked about my injectors in the past and have gotten mixed replies, but most said to "stick with what you've got". FWIW I've only gone a best of 12.61 @ 109 mph with a poor 2.00 60 ft. due to bogging at launch. So there's definitely more potential.

leave the inj alone !! we ran mid 11s @ 116+ (old blue top 36#s) for years with NO alky just race gas.. Now you have alky so it would be even easier .

 

[Quik Six]

leave the inj alone !! we ran mid 11s @ 116+ (old blue top 36#s) for years with NO alky just race gas.. Now you have alky so it would be even easier .

This answer from this guy should forever answer any questions you ever have about the injector size.

 

[TurboBuRick]

I wouldn't play around.

If you want to test the pump, jump the relay and run the fuel pressure up with the regulator screw. Should go to 100psi no problem. Yours, I bet falls way short.

 

[Quik Six]

Good post.

I plan to add this as part of check list before heading to the track.

Thanks.

 

[LITLV6]

just my .02 here but i have an issue with my 86 gn that the gauge starts to get whacky at or below a half tank. it even fluctuates to the point of changing from empty to full lol lol. i need a new sending unit and i mistakenly put my new walbro in thinging it would be a faulty ground but its still doin it. Oh, and if it starts pullin air the car will fall on its face, on or off idle. (I know, it happened to me ) good luck, i hope you find it soon.

 

[Quik Six]

I wouldn't play around.

If you want to test the pump, jump the relay and run the fuel pressure up with the regulator screw. Should go to 100psi no problem. Yours, I bet falls way short.

Did this test with battery voltage of 11.7 and FP was steady 90#'s with the regulator bottomed out.