Fuel help with Procharger

[j0n]

First some background:
I purchased an '88 iroc with a 305tpi, 5-speed and procharger p600b with a 13psi pulley. I bought it knowing that the fuel pumps wouldn't prime and now that the car is home I'm trying to diagnose the issue.

With the key in the "on" position nothing happens. After cranking a couple times something primed out back(i was working alone so im not sure which pump was priming) and then started spraying fuel out of a leaky hose so that ended the night. Today I went out and directed the leaky hose into a fuel container in order to try and empty the tank. Now with the key "on" and cranking nothing primes.

Boon believes it to be a wiring issue so can anyone give me an idea where to start looking for problems?

Also, I was contemplating doing something like a single or double walbro 255 in-tank and eliminating the fmu and auxiliary pump. Any thoughts on that?

edit: pssssst pennsyltuckey john where art thou holy self?

[V]

when will you be workign on it next? ill try to come down and give you a hand. im free anytime basically

[j0n]

well tomorrow and monday look like they'll be reserved for family. tuesday looks like my next oppurtunity.

[JSPERFORMANCE]

to eliminate the fmu you will need some bigger injectors and a custom tune.. instead if a 255, install a -8 siphon tube and an external pump such as an areomotive a1000, wire it using a separate relay and the factory harness as a trigger.

To repair a wire problem, start at the fuse and work your way to the relay and then the rear bulkhead thru connector and look for damaged or faulty parts. if everything is in order, the ecm may be messed up and not turning the fuel pump on for the initial 2 sec prime. but if you got it to work intermittently it is most likely a problem with the wiring to the pump or the realy, fuse, etc.

[j0n]

Everything I've read says that in order to eliminate the FMU I'd need to go with a different ecm, as the stocker doesn't notice boost. Im going to go ahead and run through the wires like you said and hopefully it'll start up and be good to go.

Is there any way to "trick" the fuel pump into pumping continuously in an effort to drain the tank(the fuel that is present smells awful and i wouldnt put that old **** in my lawn mower)?

[JSPERFORMANCE]

initiate fuel pump relay with scan tool

[JSPERFORMANCE]

dfi or a fast system would make things 100 times easier

[Pampered-Z]

I'm up in the mountain this week taking some vacation. Um, plan was to work on the Z this week to get ready for the race season, but all I've sone so far was look at the snow falling and not go freeze my butt off in the garage! URGGGG,,,,,

I'll be back in Ewing next week if you need a hand.

Anyway, been a long time since I played with a TPI 3rd gen, But I think the fuel pump should come on with the key, Could be a few things, ECM, pump relay, wiring, And I think the distributor wiring play a part as well. The pump will turn off if the car doesn't start right away as well. I would start by looking at the relays. Get a Fuel pressure gauge too, could be the regulator is going bad and it just takes time to build pressure?

The ATI secondard pump to boost pressure, is still turned on/off with the stock one as it just plugs into the stock pump harness. Once you figure out, you should be fine. But if you want, you could dump the two, but in my option a 305 isn't going to make that much power that fuel pressure isn't going to be you problem. I would think a 305 could go 400-425 HP max, the stock and auz pump can handle that.

But fot the record. A Racetronic single pump Kit, 255 pump and harness will support about 550HP. The dual pump about 850HP, that about the limits the stock fuel lines and fuel rails can handle. This is the basic 255 walbro with a harness that draws power right from the alternator, so the 14 volts boost the pumps output slightly. Your not going to ne near either of those numbers.

You have to look at boost two ways as far as what is needed once you go to a certain piont. 6-7 PSI is the line where once you go over it you need to do more to support it. Sounds like you have a kit that was originally a lower boost set-up that has just 12 PSI pullies. you really need more that just pullies to run that boost.

12PSI pullies will probably kill the engine quickly, 6-7PSI is about all they can tolerate for an extended time. But you can get away with 6-7PSI with stock programming and an FMU. The FMU is just a cheap fix, reprogramming would be better, making the EMC read boost is best. You don't need an aftermarket EMC. Yes aftermarket is better and they have many other benefits, but a stocker will work.

You can do away with the FMU using the stock EMC but you will need to go with larger injectors and switch to a 2 bar map. For a 305 with 8-12 LBs of boost I'll estimate 350HP. Putting that into the formula you should be about to go 80% duty cycles on 24lb injecotrs ( which happens to be what stock 94-97 LT1 use! so you should be able to finf injectors cheap!) If you make above 375, which I don't think a 305 will, then you would need larger injectors.

When you switch to a 2-BAR map sensor in order for the ECM to be programmed to read boost. You just have to make sure the person doing the tuning knows what he's doing! Once you start switching Map sensors and injectors the programming gets complicated.

Question, you didn't mention any cooler? about 7PSI is the max you want to go without an intercooler of some type, your going to be building allot of heat! So think intercooler or checmical cooler such as alki injection, That plus stock high compression you need high octane. If you plan on making allor of boost you need an intercooler and also need to pull allot of timing out of you'll kill the engine quickly. Stock pistons don't last long.

As you make more boost ( above 7-8 PSI) you need to pull timing out, about 1.5 - 2 degrees for every PSI over 6. So with you high compression ( another above 9.5 static and boost is high ) and your talking boost near the double digits I would guess at least 2 degrees. You can do thing either with tuning, or something like an MSD A6LB that can read boost and pull timing.

So If you want to go with lots of boost, get the fuel pump figured out, get a 2-Bar Map ( Autoparts store, you want a map for a Grand National, then you need to cut slots in it so that it fits the stock wireharness ), get bigger injectors and get programmed.

Another key thing to remember with a SC is NOT TO OVER SPIN IT! more RPMs makes more boost by puts the SC near it's limit where it will self-destruct. About 6500 RPMs is about the limit. Most that have tried to pust them to 6700 have ended up blowing the SC to pieces and taking out their engine.!

JB

[j0n]

Thanks alot John! This motor makes 390rwhp as is and I have a forged 350 in the back of my mind when the 305 is done for. My goal with the new motor is 500whp(not any more due to transmission choices). Thus I believe that a single walbro will be just shy of the amount of fuel i'll need. The kit is a procharger p600b which is intercooled. I wasn't aware that I can simply switch to a 2-bar map and tune with the stock ecm. I'm currently running 24# injectors. Any idea if PCMforless can get the tune done pretty good with a 2bar map? Also, I'm considering a co2 intercooler sprayer...is this going to be effective enough to run pump 93? I believe the car has an accel box for pulling timing, rev limiter, etc.

I honostly don't expect the 305 to last all that long and I doubt I'll even hit the track with it. I'd just like it to survive long enough so that I can drive the car around while the 350 gets built.

btw thanks alot I really appreciate all the time and effort you put into all your replies!

[Pampered-Z]

Wow! 390HP out of a 305 on 24lb injectors. That pretty amazing. The FMU must be raising FP to 70-75 PSI in oder for those injectors to support that HP. You might want to get a scan and see where the duty cycle of the injectors are. I'm thinking you way up there!

You've got a goot handle on your setup. If you don't have something pulling timing out I would suggest running high octane!

500HP is a good target, and about the max the little P600B can make. I'm running what are 15lb pullies which put the max RPM of the engine at 6400. Having a front mounted 3-core intercooler and a 383 means the SC has to work hard to fill all the volume, and as such I only see 10PSI on the gauge at around 5200 then boost starts to drop as the little SC can't feed my set-up. I made 470 RWHP with a bad tune, so I think 500RW is the max. I'm running the single Racetronics pump and harness and see no drop in fuel pressure at all and duty cycles are 82% (42LB injectors).

Well If you go with the 255 intank and the external I think you'll have enough fuel. For 500 HP you will need to go with at least 42LB injectors.

Yes, PCMforless can do the tune. If fact of all the local and other tuners Alvin was the only one that backed up his words with his work! Alvin runs a few SC speed density cars of his own with a 2-bar map and had a base tune for a 355 LT1 that was close to my setup. Alvin sent me the first tune adjusting for 383, 12 PSI, 42 LB injectors, 2 bar map. Car started first try, had a slight flat spot off idle, and was real rich at WOT, but I told him I wanted a safe tune. On TTPs dyno it made 470 RWHP and smoked like a diesel!. I send Alvin a data log of the car with about 10 minutes of scanning from normal driving to a run thru the gears at WOT, and also a copy of the dyno sheet. He made the changes and the car runs amazing! He'll be coming to PA soon and I intend to get him to do a full tune on the dyno, I think the key is getting the timing tables right to match the air/fuel under boost is the key to getting an SC engine to run well and live long.

Once my daughter is out of college I'd like to move up to a D1 or F1 and maybe aftermarket heads and ptu the boost above 15 and shoot for 750HP. But that means upgrades to the entire fuel system, pumps, fuel lines, fuel rails injectors ets. At that point I'll drop the stock ECU, mainly because I have an aftermarket system that has extra functions such as full data logging, two step, being able to turn on a secondary pump under boost and activate alki or nitris at certain boost+ RPMs.

JB