diy: fmu repair

[neverlift]

well ladies and gents again my cheap side has figured out yet another free solution to another problem, this time a 45+shipping dollar problem!

does your second hand fmu just dump fuel in the 100psi range no matter what? did you replace the upper portion of the fmu to have the same result?

well I did even if you didint I'll get unlazy and snap a pic or two later, but it is simple, inside the lower portion of the fmu is another silicone diaphragm,a rubber oring,and a metal disc.. well in my case I finally took it apart and saw that the metal disc was creased and had a small whole! After sitting in the workroom for a few minutes looking at it and slamming it on the table I realized it did not sound like metal, grab a magnet and test my theory ! I am right, it is aluminum! SO, I quickly grasp a mountain dew can, kill it like I have never tasted the sweetness and cut it the f*** open and make one(it is nothing more than a circle), reinstall all the parts in order as removed, and go put it on. Guess what it works, like a charm.

I'm sure this will fail at some time, the stock vortech disc most def is prone to failure just by looking at the disc used(thinner than an aluminum can lol). So I will most likely update this thread or make a new one.

btw it has hit 8psi so far and performed flawlessly! hope this helps someone
Modified by neverlift at 2:52 PM 7/23/2009

[Razi]

Cool fix!

[eazye2000]

LMAO I love it! That's an awesome idea.

Not to jack your spotlight, but I fixed my eBay BOV diaphragm with an old bicycle innertube. lol

[neverlift]

thanks manit works just as it should is the shocking part, my wife watched me make it,well she helped cut it out cause I failed scissors in school and just suck at cutting along the edges, I know she thought I was nuts cutting a can up smiling but then realized I just kept 50 bux in our bank account...

I may actually go a step further and replace the rubber oring but at this point its testing to see how long it will last, if I had a better cam you could see almost half the circle is cut/wore through from being used.

I know not many will appreciate this or try it for that, but it is now an option, and I hope anyone who sees it tells 50 people, the way that rude mother f***er was from vortech I wont be buying anything from them first hand. Had they responded to one of my emails with ef off I would have been happier than calling them just to get some f stick tell me I need to buy a rebuild kit, "that may fix it , if not you will need a new unit which I would be happy to sell you right now" I called tech support not sell me s*** support looks like I am laughing now f'ers

[neverlift]

oh thats another great fix, you should have posted it up, I am not a poor guy by any means but I dont like to buy something if it can be fixed, my car should have been sold long ago lost count of how many times it has broke... yet I cheaply fix the pos. I would have bought the thing from them but was ignored via email then was asking tech questions, to tech support,and the guy tried to sell me a new unit...

anyways I'll continue to cheaply fix things until it gets old, but with the fire vortech lit under me how could I not!

[WDRacing]

I know not many will appreciate this or try it

And F anyone that doesn't appreciate it If it weren't for us DIY guys we'd be riding friggin horses still.

Good job man, using a Mt Dew can is awesome. I used a Pringles can for a wireless directional satalite. Red duck tape, cardboard and half the pringles can. I improved my signal strength 11mbs on the other end of my house. I can now stream movies anywhere in my yard Ok by movies I mean pron But whatev right

I'm tempted to use a Super FMU, twin pumps and see just how many psi I can run before I get injectors leaks

WD

[neverlift]

well my s*** hit fmu was bad my injectors saw 100psi at idle and they are still in use, I know a guy local ran 12psi on his t3/t4 setup and made some 300whp walbro fmu timing retard and balls.

In reality I have ran 12psi of boost with 70psi fuel pressure(had to be making 300whp I dont think I can drive or anything but it was a hand full!) and 5degrees knocked off the dizzy. Now running same 5* off the timing and the fmu,walbro,afpr. It is a hair lean for me right onto boost but the car is quicker now in that area for sure, I am going to add some base pressure with the afpr, to have more where I want it, then bleed off or some of the boost pressure to reduce the overall gain. But first I am going to redo the vac lines, I have the fpr,bov,and fmu on the same line... Now its fmu/boost gauge on the booster line and just the fpr and bov on the other. The fmu is also getting a smaller diam hose.

wd thanks it means a ton

I have ridden a horse, it sucks.

that is awesome send me more on that, I have a friend who is always complaining about his wireless while gaming, the lag is retarded.

we know, you pron fluffer

I am curious as to just how much myself, what can a single hp walbro255 put out? its ran on the relay mod btw. I think top feed would be more prone to get stuck, the S/F can basically free flow the pressure in between themselves rather than build up on top.. but IDK enough to make that call. I have 370's I am ditching in favor of the fmu. If I can get it to not max 80psi with 12psi I would run it daily damn that ran long

[VeloceDrift]

nice! well at least i know when mine goes bad i will do that for sure.. One question though.... Suppose i can use a Dr. Pepper can??

[WDRacing]

One way to assist the fmu overcome the intial 3-4 psi rich factor is to add a can or vacuum block type of thing between the vacuum source and the FMU. This will delay the signal by a slight bit, but that slight bit allows the turbo to make 2 maybe 3 psi so when the FMU gets around to adding the fuel, the motor actually needs it. Because the stock injectors and MAF are good all alone until 5 psi or so.

Experiment at your own risk. But I've seen a soup can used with 2 vac bungs jb welded on. The transition into boost was WAY smoother.

WD

[neverlift]

I will have to try that wd, but first I need to figure out why I hit vtac at 5300 rpm? I'm thinking cts there is at least a 30~45whp gain at 5300ish rpm? anywho, I'll scoop a can tomorrow from the j/y. ? though, I am running 7psi so I am already around 80psi at times, would this let me run another psi or two of boost and still only see that 80ish psi of fuel pressure? I would like to max this thing out on the dyno one time on spring pressure, if I could drop 4psi off the fmu(that would let my fuel pressure be around 60psi) and run an extra 4psi without extremely stressing the system as I know 80psi is plenty for 11~12 psi. or should I find a way to went a few psi? dont wanna pop another motor too soon,but I want to see whats up as well.

My knock sensor is f***ed and unplugged but it has always been like that. Anyone know off hand what rpm the knock sensor stops reading? I would assume way before 5300rpm?

NO! it has to be mtn dew

[Razi]

How long have you had your FMU setup?I've had mine for about 6 months and it's been good to me.

I recently took off the FMU and got a tune though.

[neverlift]

only a few days now. I dont know how long it was used before it broke, bought it used...

I have some 370cc injectors I actually thought about the suby mod where you shave the disc off( IIRC something like 700cc when using the 370cc to start) but I am not sure how easy it would be to tune as latency an what not would stay the same but p/w would have to hit the floor... I dont intend to waste anymore time with the thought of sr injectors as they are not enough fuel to have a decent overhead for improvement. I know a guy with some 550's for a buck fifty, but they are msd top feeds:( first I'll tinker with the fmu stuff, a local guy ran 12psi on an 8:1 and made great numbers on the dyno. I want 12 daily lol.

[neverlift]

well I replaced my cts and fixed the knock sensor wiring(it got ripped off) and I'll be damned at the 100+whp gain throughout the rpm range.

wd I added a little can thing I found at the junk yard today, it takes about a psi or two to blow through it(reference from blowing into my vac gauge ) I need to run my pressure gauge to where I can see it in boost(or try a h/f oil pressure gauge that only goes to 100psi) but I know its running real nice right now, I may dyno the cheap mans setup... check with the wife, it kinda seems like a joke, I could put that towards a night at gville but damn that is a ride. weigh it and use the 10year old gtech blows doors off a 05~06 civic si, from 70 in 5th I am calling my boy with his sr and its time to see whats what.

[neverlift]

WD little help man? I ran a line from the gauge port to the gauge on a 3foot piece of 1/4, my pressure spikes to around 90psi then bleeds off to around 60(hard to tell as I am trying to drive this monster and keep an eye on afr and fuel pressure) but then wants to stay around 55~60 psi on the gauge. Is that from the small diam hose and being long it just takes a minute for the pressure to equalize?

is the can I added reason for the pressure to drop off? if yes maybe I need to go about this a different route, try bleeding air before it gets to the fmu? or run a ball valve to limit the flow going to the fmu? I'll remove the can I added and see if pressure jumps and stays higher, afr are all good when the pressure is dropping btw.

with my math I can easily run another 3~4psi of boost and still be under 90psi. When the wife gets home I'll be doing some more runs to see what is going on.

[neverlift]

I know this has changed....

anywho I pulled the can and the spike is the same and the drop off is still there, I moved the gauge back as I think it might be part of the fall off,prob not falling off just looks like it on the gauge, I'll try a h/f oil gauge in a few days, just to see if its the long fuel line...