Can a fuel pump be too big???

Hey guys I’m confused and probably missing something really simple! I run a blown alky 427 ci, 10.8:1, 22lbs of boost, injected w/ .045’s in the hat, .035’s in the ports, 25 degrees timing, MSD digital 7 ignition w/ Mallory unilite distributor, no mag. I’m running .019 gap in my plugs. We can’t get the motor to RPM under a load. In neutral it seems to rev up just fine, but with the trans brake applied and revved up to around 5000 it begins to sound like a rev limiter is coming on and it falls on it’s face and will almost die until I let off of the throttle. The data logger shows fuel pressure to mimic rpm just like it should. There’s no pressure drop before rpm drop…only initially due to the barrel valve opening. The pump makes over 100psi according to the data logger when I first hit the throttle. I run a Hilborn PG 175B-2 pump that puts out 12.3 gpm @ 4000 RPM/100psi. Right now we have a 145 main pill. EGT’s are anywhere from 400 to 700 at idle and never seen any of them go above 1000 @ higher RPM, granted we haven’t been able to make a run yet. I’m running the idle check and pump relief out of the k valve back to the tank. Is it possible we are washing down the cylinders at high rpm because our pump is too big and not bypassing enough fuel? Any help would be great!

Josh

 

josh, first off i don't think you are running enough timing. you should have 28-30 degrees. (my opinion). second you state you havent made a run. ....... there is no way to tune a motor on jack stands. yes you can look at idle temps but you cant try to tune by bringing up the rpms to (lets say) 6000 and think it is simulating a run. at 6000 on the jackstands the blades on the injector might be open an 1/8 of an inch compared to going down the track with the blades wide open. at 6000 rpm the pump does not know the position of the blades or barrel valve. but when the blades of the injector are wide open the spool is in a different position and the amount of air going in the injector is greatly increased which completly changes your air fuel ratio. did you get the fuel system from a reputable person who knows fuel systems . if this is a starting point given to you then go out and do a burnout . if it seems o.k. then stage and make a pass to about the 1/8 mile or shorter until you are comfortable. just keep an eye on your cylinder head temp while it is running. if it is too hot after a burnout shut it off. if the temp is o.k. try your check out pass..... hope this helps.

 

Hey Bruce I agree 100%. Can't tune on stands, nothing simulates a run better than a run itself. The whole fuel system is brand new, pump, hat, nozzles, k valve, etc. I forgot to mention...we have been out to the track twice now with no luck. Heck this week I took it out on the street to make sure it would work before going out again. At the track I would start to do a burnout and it just lost power as soon as the RPM's went up. It just won't hold power. I had it on a chassis dyno about two months ago and it seemed rpm fine under a load, but we ended up blowing a head gasket because we had a port nozzle that wasn't drilled.

 

At what rpm is it making 22 pounds of boost? Under load or not?

 

it's a tri-stripped 871 @ 21% overdrive. I've seen the data logger report 22 lbs at 6600 rpm, but 19-20lbs is a more steady reading.

 

if you have a filter between tank and pump inlet , clean it
Claude

 

Make sure the spool in your fuel shutoff is in correctly. Sometimes we have seen where the person wants to put the cable in a different position, and so the turn the spool around. This will run and idle, but won't run. Would be something to check anyways. A 12 gallon pump should go down the track as Will said. Also, make sure the rotors are in correctly, you can put them on the wrong sides...it will run, like a tractor, but not very well!

 

Josh, I talked to you a little at WIR about your troubles. I still blame the unilite. Another site that might help you out is HRE.com. Mostly,dragster guys but, some real sharp fuel system and ignition knowledge.It costs $$$ to join but it can save you a lot of misery.

Good luck,
Mike (orange 69 Camaro)

 

Josh was that 6600 during a run, on the dyno, or on the jack stands? It makes a big difference.

 

I beleive that was on the dyno pull. We've talked to enderle and hilborn, both think that the pill we're running is too small being a 135. Guess we'll lean'er out some more and see what happens.

 

We had the idle check valve in backwords once and would do ok till we put a load on it. We used up a few pop off plates till we found it

 

A 145 in the main!!!!!!!!wowo

 

try this....

I had a very similar combination with very similar response. I changed my coil to an MSD HVC-2. Like adding a Mag 44 type difference! Will work with the 7 box, but not sure about a 10? Worth while investment. Ed.

 

All of the suggestions offered are good, but have you considered it may be too lean?
On a 400 in. small Chevy with a PSI and underdriven LiL Bertha @ 13.5 gal; we used 10 dribblers between .052 and .060 + 8 port nozzles from .035 to .038 with an .080 main jet! Granted, this was with 42lbs boost not 22lbs,but we ran a linear fuel curve with no Hispeed to 9800 rpm.
How good an engine do you have; cylinder heads etc.?
It is possible to be too lean to hurt anything! If it is as rich as you think; it should be throwing fuel out the pipes like Crazy!
CMD

 

Flyboy,
Fueller42 has a thought, what coil are you running? If not an HVC coil, get one!! You cannot run alky with a blaster type coil under a load. We ran 7.70's with a MSD 6al with an HVC coil on a blown small block, car popped and farted with a blaster coil. Also IMO, get rid of the unilite, get a billet MSD dist., best $280.00 you'll spend.

Keith

 

Just a thought!!!!!!

Have you looked at the settings in the digital 7 box. The box contians 3 different rev controls. I just learned that last week. We bought a nitrous car to play w/ until are blown outlaw car gets here. You need to look at the settings in the box and look at what the model number is on the box some of them have more stuff in them than the one we have. If you have any questions give me a call @979-429-3533. I am still not ruling out the fact the system may not be enough or enough timing.

 

Hey guys I appreciate all the help! I do run the HVC II coil. Over the weekend we figured out what it was. Two things...the alternator was putting out .5 volts of AC current, we unplugged it and it worked a lot better but was still cutting out a little on the top end under a load. I probably should've mentioned we run an alternator in our outlaw 10.5 car. The main thing was our distributor cap had a small spot where it was shorting out along the coil wire opening inside the cap between #1 and #3. Replaced the cap and all works well. Just thought some would be interested about what it was. Thanks again for all the help!

Josh

 

Now thats what i like to see, the problem solved and the reason posted, nobody knows everything, good to see somebody takes the time to post the reason why, to all the answers that peopel posted answers too.