Check my vbgarage just in case, but I'm running rtek 1.7 with 720cc secondaries.

I've been continuing to run my stock T2 fuel pump which hasn't given me any problems until (I think) recently. I removed the hi flow cat yesterday in exchange for a straight pipe, now I have a completely unrestricted exhaust and intake and my boost has gone from 7 to 10.

However now my vehicle when revving past 5500-6000 RPM's is experience severe power loss and acting like it did when I was hitting fuel cut on my stock ECU. I can't say its the exact same because the cut only removed fuel from the rear rotor, but I believe the only reason for the difference is (I think) because there isn't any, or enough, fuel going to BOTH rotors this time.

I need to know if it is just my fuel pump not keeping enough pressure on the line so that I can replace it with a walbro. What I need >MOST< is your opinions regaurding the loss of power, because my funds are tight and if it isn't the fuel pump, or if there is any other possibility that it's something else, then I need to go get it diagnosed because I can only afford one upgrade/repair right now.

Thanks for your help guys and let me know if you need any other information.

-Landon

 

I don't think there is any definitive way of telling without putting a fuel pressure gauge in the feed line to the engine and watching it while driving. That's the cheapest way of telling.

Another way is a wideband meter, but your on a budget and that's out.

I KNOW you can run to ten psi with the stock pump and stock 550's without losing fuel pressure. With 720's? Got me.

 

I had typed out this extravagant response to what you said Hailers, then I realized you were talking about a pressure "gauge" and not a pressure regulator so I had to start over lol!

Okay, a fuel pressure gauge... sounds do-able... gonna do some research into them now..

But if you or anyone else could give some more insight onto my shituation. I would greatly appreciate it!!

 

Okay, just for peace of mind I went ahead and bought an ebay autometer FPG.

Do I just put a T-junction in my existing fuel line and run this to it or what?

http://cgi.ebay.com/ebaymotors/ws/eB...tem=4647560542

Thanks again!

 

I found that the most expensive upgrade I ever made was the RB race use only (no cat) exhaust. What happened? It pulled hard!! then blew up within a week! the cause, insuficient feul resulting in detonation. The moral of the story is upgrade the feul system anyway ASAP it will not hurt but may save thousands. Be very careful till you know the problem.

 

That gauge kinda worrys me. Something isn't quite right about it.

You just need to tee into the line b/t the fuel filter and the hard line that connects to the engine. At idle you'll read about 28-32 psi. Under full boost at ten psi it should have risen to about 47-50 psi. IF it does, then there is enough pressure from the fuel pump imho.

 

Wow thanks for the information hailers and tin!

Also, call me an idiot, but what does detonation in the engine feel like? I haven't been in, or seen, a vehicle that's detonating, so I don't think I'd recognize it if it happened.

And more specifically about my power loss. "A walkthrough"

Put the vehicle into heavy acceleration, foot to the floor, boost starts going up to 6 PSI at around 3000 RPM's, smooth acceleration in whatever gear I'm in, boost steadily climbs to 8 at around 4600 RPM's, then without warning somewhere around 6000 RPM's, the engine stops making noise and the car bucks backwards, after about half a second the engine fires up again, accelerates a tiny bit more, then repeats the problem until I let off the gas a little bit. The boost during this time fluctuates between 8-11 as the engine is cutting off and on.

I've only created the conditions that cause this problem a few times to gather information. And haven't recreated the problem since.

Oh and the problem ONLY happens during hard acceleration when boost goes past 10, and drives perfectly fine under normal driving conditions. I don't know if it's a boost related problem but since it only happens when the boost is high I'm not ruling it out.

And Hailers, do you have anything in particular you don't trust about the fuel gauge? Have you worked with many before? I compared it to other autometer's like it on ebay that were more expensive and still in the package, and other than the fuel line being as thin as my boost gauge's it looked identical to the others.

 

About to hit the hay.. I'll keep you posted on my progress, but I'm still fishing for ideas!

 

You can't feel detonation and often you're lucky to even hear it. To give you an idea, pro dyno tuners use amplified earphones with special microphones clamped to the engine so they can detect detonation early. Particularly bad detonation sounds a bit like someone rapidly hitting the engine with a ball-peen hammer.

Personally I believe the fuel pump should be upgraded at the same time a FCD is added. If you really need upgraded secondaries, you really need an upgraded pump.

 

Okay I did this research a long time ago and because of the literal flood of search returns and name drops, I am not getting my specific questions answered about this fabled "walbro" fuel pump so I'll put em here.

For this set up do I want to buy a low pressure lph 255 walbro or a high pressure one? Do I need to change my fuel filter to some kind of higher pressure or higher flowing filter? I've already read the re-wiring how-to's. And the extra pressure in the fuel line, obviously will reduce fuel economy, but will this pump add any noticable power in acceleration?

 

You don't need to change any fuel filters, but, while you have the tank open..it's a good idea to replace the fuel "sock", as it is normally disregarded as necessary to be changed.


I'd do a full tune-up while your down for the Walboro and fuel pump rewire..change the fuel filter(s), spark plugs, wires, etc...theres always a chance the fuel filters are the cause. Might as well eliminate the possibility..

 

Do NOT install that gauge *IN* the car. A leak would pump fuel into the cabin. Those gauges are to be installed outside of the cabin.

For what you want, I would also recomend ditching the compression fittings and plastic line and go with AN fittings and braided hose.

 

None at all, in fact it'll make the mixtures slightly richer, reducing both average economy and power. Not enough to worry about though. Power only increases if you increase airflow and/or make the AFR leaner.

The car isn't going to be "down" for a fuel pump change and rewire. The rewire takes 2-3 hours depending on your confidence with wiring, and the pump swap can be done in under an hour.

They can be safely installed in the cabin if you use a proper isolator designed for fuel pressure guages.

 

Oh yeah, I completely forgot about those gauge isolators. Probably cost more than the gauge though.

 

Frankly, I just bought a regular fuel pump gauge from the auto store. It wasn't cheap either. Around fifty or so. I cut the end of the hose off and bought a Tee that fit the gauge hose and the fuel hose on the car. Then bought a couple of feet of fuel injection hose to lengthen it. Not cheap hose.

Tied this to the windshield wipers and drove the thing. Now if Wayne was still on this forum he'd tell me how this is not a safe thing to do. Nah.

Anyway, it let me KNOW what the fuel pressure was at full boost, instead of GUESSING as is done by others. If your at full boost and the pressure rose a full psi for each full psi of boost, and the pressure did not fall off as you stayed in boost, then I say that's good enough. Is for me anyway

 

Where'd Wayne go anyways?

 

I'll admit I learned the hard way about useing FI hose. USE IT. Don't get regular fuel hose, make sure it says "fuel injection" right on the hose.

I've done the same thing with an "external" gauge....tied it to the wiper..good enough for testing.

 

That's still better than what I did. I found a suitable pressure gauge (literally found under a pile of stuff at work), got a brass tee and some leftover fuel injection line and ran it into the cabin! A mate held the gauge in his hand and watched while I drove. He also held a rag under it to catch a slow drip because I forgot to use thread tape. Ten minutes of testing, job done, performance confirmed, gauge removed.