Fuel Pump Destroying my MPG?

[BlackMount]

FYI I did some searching on this and it really didn't help me

I have 1990 Laser RS Turbo

engine Mods

5 Speed
MBC set @ 15 PSI
14B Turbo
Tubular Manifold
Aftermarket Fuel Pump
Oil Cooler
NGK plugs
Stock Injectors

bought the car about a month ago, and just recently I have been getting REALLY bad gas mileage. my last tank of gas lasted me 170miles (and I had been babying the hell out of the thing)
The first time I filled the car up completely when i bought it I got about 240 miles on a single tank (and I did alot of ZOOM ZOOM that week too including more then 1 Top Speed Run 139 so far )

Part of it is because I have a bad ECU, but I've HAD a bad ECU and i had decent MPG before.

just today I was doing some errands, and I hopped on the interstate for a good 2 miles, and it drained 1\2 a quarter of my tank. In town if I baby it, i get pretty decent MPG it seems.

Is it because of my Fuel Pump? I don't know what pump exactly it is, all I know is it probably the typical Walbro 190LPH or 255LPH. If that's my Fuel Problem I will Happily trade for a Stock Turbo Fuel Pump straight up, no strings attached. I don't need this fuel pump because my car is a DD, and I don't do serious enough racing, or push enough boost I think to need it.

P.S (My Fuel Pump has not had the "Re-Wire" could this be part of my problem?)

HELP

 

[LiquidX]

First off, you want to get your ECU fixed. If it has leaking CAPS you can get to posibility of causing some havoc to the car. Send it in and they'll fix it up for you ECMTuning, Inc.

Next, you have an upgraded fuel pump without an AFPR. That's your issue right there. You are over running the stock FPR and going rich.

 

[BlackMount]

First off, you want to get your ECU fixed. If it has leaking CAPS you can get to posibility of causing some havoc to the car. Send it in and they'll fix it up for you ECMTuning, Inc.

Next, you have an upgraded fuel pump without an AFPR. That's your issue right there. You are over running the stock FPR and going rich.

Thanks for the input

I've looked into a ECU rebuild, but I'm worried it will cost more then just buying a used one. another problem is this is my DD, so I cant send in my ECU because then I cant get back and forth to school\work.

I'll look into buying a AFPR, Money's tight so hopefully I can afford one.

What I'm trying to do right now is get my buddy to trade me a ECU + stock Turbo Fuel pump for my walbro 255lph (I did just now find out it is indeed a 255)

 

[ramsack]

i'm in the same boat as you are. my fuel pump was dead and the only one i could find quick was a 255hp for free. now my car runs rich as hell, and i can't afford a afpr at the moment. i'm not gonna trade down to a lesser pump tho, i will just wait for an afpr.

 

[94TalonTSI1]

The 1G FPR can handle a 255, just not the HP one. At idle, you'll get a bit of FPR overrun, but otherwise you are in good shape. I've run one without an AFPR on my old 1G, and had no issues.

Your ECU is definitely not helping matters. All the pump does is push fuel through the lines, your injectors tell how much fuel to inject. If you have the 255HP, your fuel pressure will be bumped up a bit, however if it was that rich, you'd notice a loss in power.

I'd look for some boost leaks as well post MAF. Your Fuel Pump Rewire won't have anything to do with it, however if you are running 15psi, I'd get on that isht ASAP!

Do you have emissions on your car? The EGR system will increase fuel economy and does not rob HP. Tim Grech, a Mod on here did a great write up about the Emission system and why it's a bad idea to remove it. The only benefit you have is a cleaner engine bay.

You could also look at exhaust leaks pre-turbo as well.

 

[blownturbotsi]

Do you vent your BOV to the atomosphere?

 

[GRAVEDIGGER]

A top speed run? Wow! No speed limits in Tennessee huh?

 

[snakeyes711]

harbor freight has pancake compressors on sale right now for 39.99, and a 25ft. hose for 4.99. I'd get one of those, and boost test to start. I'd def. pull the ECU, and look at the caps.

 

[BlackMount]

The 1G FPR can handle a 255, just not the HP one. At idle, you'll get a bit of FPR overrun, but otherwise you are in good shape. I've run one without an AFPR on my old 1G, and had no issues.

Your ECU is definitely not helping matters. All the pump does is push fuel through the lines, your injectors tell how much fuel to inject. If you have the 255HP, your fuel pressure will be bumped up a bit, however if it was that rich, you'd notice a loss in power.

I'd look for some boost leaks as well post MAF. Your Fuel Pump Rewire won't have anything to do with it, however if you are running 15psi, I'd get on that isht ASAP!

Do you have emissions on your car? The EGR system will increase fuel economy and does not rob HP. Tim Grech, a Mod on here did a great write up about the Emission system and why it's a bad idea to remove it. The only benefit you have is a cleaner engine bay.

You could also look at exhaust leaks pre-turbo as well.

The Car has had a "Emissions Delete", not by me, but by the previous owner.

I have read that Write up and it is a great write up, and I've never really found "Emissions Deletes" necessary.

I haven't had time to go through and track down what goes where and reconnect everything.. some things such as the Canister under the battery, and EGR valve are just left open, and not blocked off or anything. but like I said Gas mileage was great when I first got the car, and I haven't done anything to the car that would make it worse. if anything a few things I have done that you'd think would help make it better, such as clean air filter, gut the MAF, etc. and I've gone through everything as far as boost leaks and exhaust leaks go, and I know I don't have either.

A little note, The only time I smell Gas in the car, is when I hop on the interstate.

I can beat or baby the car all I want in town and never once smell gas, but for some reason as soon as i start cruising at 70-80mph I start to smell it.

 

[ramsack]

my car will knock as soon as boost hits anymore too. way too rich. no boost leaks and timing is dead on. the knock just seemed to come outta nowhere too.

 

[BlackMount]

A top speed run? Wow! No speed limits in Tennessee huh?

I failed to see any signs

5 Lanes Wide, and not a car for miles you cant help yourself sometimes

to answere other questions.

I completely re-did my plumbing after finding several boost leaks about a week ago, and tested after, and not a single leak anywhere.

I am not dumping my BOV into the Atmosphere.

 

[midnightprod]

hey, i thought you dont need a n afpr with a walbro 190.

 

[DearestNameless]

If you do want to trade for a stock pump LMK

 

[gstryyder]

if it is your pump.. i have a stock 2g gst pump... cost of shipping. like 5 bucks.. if it will work on your car.... you can have it. it is used. but works just fine. but i have a feeling it is something else. and when is the last time you changed the fuel filter?

 

[BlackMount]

Fuel Filter is like brand new. I'm suddenly getting better mpg, not sure why.... I think my ECU might just be Bipolar. some days the car runs amazing, others i cant drive faster then 55

 

[99gst_racer]

Have you verified that your O2 sensor is cycling and in good shape? A dead O2 sensor will kill your fuel economy.

Also, scan across your entire fuel system for leaks. Check around the tank seams, the fuel lines (feed & return), the filter, and both ends of the rail. You really shouldn't be smelling fuel while driving down the road.

In any event, unless your car spends more time idling than driving, it's not your pump that's causing your poor fuel economy. I run twin fuel pumps, 1200cc injectors, and 40 psi of boost and I get 27 MPG. You should be getting close to that same MPG.

And what exactly is "bad" with your ECU?

 

[BlackMount]

No external leaks on my DSM. I have new grommets, and o rings for the injectors. and i smell gas If and Only If I cruise on the interstate.

I don't smell it during acceleration even if its hard

Only ON the interstate. i cruise about 3.5K at 75-84 mph. (80 mph is plenty safe from cops in TN)

My ECU has small Burn Marks in places. It's causes a slight miss at idle which makes it unstable, and causes me to cut out at 2-3K rpm's if I'm not at full boost.

We put my ECU in my buddy's GST and it did the exact same thing, then once he got a good ecu, he tried it in my car, and it ran perfect, and runs perfect in his GST too.

 

[99gst_racer]

Well, it sounds like you know exactly what your problem is then.

Time to start looking for a replacement ECU if you can't afford the downtime associated with sending yours off for repair.

 

[BlackMount]

Well, it sounds like you know exactly what your problem is then.

Time to start looking for a replacement ECU if you can't afford the downtime associated with sending yours off for repair.

I have like 3 Turbo ECU's, none work. I was told none of them are repairable.

All my other DSM friends either have broken ones too or Non Turbo's

I've looked at a few on Classifieds but money is also a problem. Billz Billz and more Billz, and I have a Window Tint Citation I might have to pay. I have court for it today, hopefully I can get it dismissed since I pulled the Tint Off.

 

[LiquidX]

Unless the board itself is broken, it should be fine to be repaired. Look at ECMTuning, Inc. and they can most likely repair the ECU for you.

ecurepairhome [ECMTuning - wiki]
Services

 

[99gst_racer]

Steve does great work too, and his turn around time is impressively quick.

DSM (Talon Eclipse Laser) and 3S (3000GT and Stealth) ECU Service and Repair

 

[LiquidX]

Steve does great work too, and his turn around time is impressively quick.

DSM (Talon Eclipse Laser) and 3S (3000GT and Stealth) ECU Service and Repair

I've always wondered about this "Steve" person you are mentioning. Thank you for that link so I can now offer a second place to send people than just one place

 

[tragdor]

Steve does great work too, and his turn around time is impressively quick.

DSM (Talon Eclipse Laser) and 3S (3000GT and Stealth) ECU Service and Repair

+1 on Steve-He's very honest and will give you a fair price. His turnaround on my ECU was really fast and he wrapped it better than I sent it out to him. Good guy.

 

[SpeedAddict62]

1. Send your ECU into Steve, get it fixed. He knows what he is doing and if it can be fixed, he'll take care of it.

2. Fuel pump is not your issue. I ran a 255HP with no AFPR for a long time. Yes, it overruns the stock AFPR at idle and cruise. No, it doesn't make a big difference. It is well within the capabilities of the stock ECU to compensate by closed loop running. So unless you want something shiny in your engine bay, save your cash, get the ECU fixed, and do any other required maintenance.

 

[ramsack]

fix your ecu first, then get an afpr. mine is being overrun and i know it is because if i unplug the vac line going to it, it doesn't change how it runs one bit, and it misses at higher rpm like it is leaning out, and i have terrible knock. i tried 2 different stock ones and they both couldn't control fuel pressure properly. if you don't have a 255 HP don't worry about it then, but least you could do is check that you have proper fuel pressure.