Walbro fuel pump issues. Need some advice.

Hello everyone.

Ever since I installed the walbro fuel pump with the 7th injector kit it’s been a problem.

1. It won’t stay primed. I either have long cranks or crack twice.

2. It screams when it’s anything below a quarter tank and when it’s hot outside. Really only noticeable at idle and seems to get louder at idle. And it makes weird noises when the fuel sloshes around coming to stops.

3. I get fuel surging randomly accelerating sometimes. STFT goes up to 12+ so it’s leaning out.

4. At idle my LTFT is at 12.5+ Which seems high. While driving I’m at 6-7+


I also believe a have a very small exhaust leak right before the AFR o2 sensor. So it could be adding to the problem.

Anybody ever experience any of this?

 

I’m having some issues with my entire setup. Everyone I talk to who has the Walboro 190 says it screams like a stuck pig when it’s under any sort of load. I have the same issues albeit my LFT is a bit higher than yours. Do you still have your stock pump?

 

I think so. I’ve been thinking of replacing with a AEM pump. But if you read Gadgets website he says the walboro is perfectly sized in both GPH and voltage. Not sure what to do.

I’ve also spoken with Gadget about this. He didn’t seem to have ever had experience with these issues.

Also need to add that mind only seems to scream at idle, slow speeds, and aiming to complete stops.

 

I had a weird issue with mine on a drive back from Vegas where after a 2 mile long somewhat steep uphill drive, my gauge went from quarter and slowly drained itself and the engine started sputtering real bad along the flat part of the road. So I pulled off to the side and got out to look around and the pump was absolutely screaming but otherwise nothing was wrong. Got back in and tank was back at a quarter. I thought about trying to toss the stock pump back in to see ho it does under normal driving.

 

Sounds like it sucked up all the fuel and bogged it down and didn’t have the time to return it. I had a similar issue when I was tuning and went for a WOT. It was going until it just slowed down and lost power. Immediately let off the gas. Figured it either went lean or rich by a large margin. Won’t be doing that again until everything else is 100%

Wondering if this could be voltage related. Pump thinks it’s gotta go super rich for some reason.

I installed everything at 109k. What about you?

 

@crashnburn80. Didn’t have anything for us. Probably not a good sign...

 

Mine was at 175. I’m thinking stock pump and see if idle trims fix themselves

 

Not sure where I fit in here, but it sounds like the starting issue is due to a bad fuel check valve, meaning the system has to be reprimed before starting. You could try simulating multiple starts by turning the truck to accessories only for many seconds, then off, then accessories for many seconds, then off, then to accessories before starting. The pump will have then primed the system and you will have narrowed the delayed start to a lack of fuel pressure issue.

I’ve read plenty that Walbro pumps are loud, especially at lower fuel levels. For this reason I paid the trivial amount extra and went with URDs Deatschwerks pump instead. Haven’t installed it yet though, so no first hand experience yet.

 

@Shortman5
My Walbro pump whines quite a bit when it gets hot, usually on a hot day when I'm slow speed wheeling for a while - probably why they're nicknamed Whine-bros. I haven't noticed any adverse performance from it though.

Your stock fuel pump will not keep up with the demand from the 7th injector, it is barely high enough capacity for the six stock injectors. I would not reinstall the stock pump unless you had no other choice. A higher flow AEM would be fine - the fuel pressure is regulated by the fuel pressure regulator, so a higher flow pump shouldn't "overpower" the regulator and cause a rich condition. Having a malfunctioning pump or an undersized one could possibly cause a lean condition though.

Your fuel trims are definitely on the high side, my LTFT slowly raises to 10 or 11 while idling, and the STFT bounces around from -2 to 2 or so. Under mild load they both go to zero, and at WOT they are around 3-5. I figure the ECU is trying to compensate somehow for the 7th injector controller, which is why the trims go up at idle, but I'm not sure exactly why. @Speedytech7 might have a better idea of why this happens.

@crashnburn80 I believe the 1st gen fuel system only powers the fuel pump during cranking, so just turning the key on will not prime the system unfortunately.

 

Been a while since my first gen. You can usually hear the pump kick on under the bed when in accessory mode to test.

 

At what PSI do you have overpressure set to? And did you actually zero fuel trims with the 7th injector?

 

I actually have the stock tune on the 7th injector controller, I believe the overpressure is pre-set at 4psi. I've been thinking about dropping it to 3psi to avoid lean tip in, but I'm not sure it needs it.
I haven't tuned any fuel mapping with the 7th injector.

 

Im seeing if it fixes it being lean at idle. Im not planning on actually driving with the stock pump in. If it still idles at 19 LFT with the old pump in, then theres an issue with something else. After everything I've done it points to the injectors. If it idles at near 0 LFT it was the pump.

 

Damn. 19? Are you running stock maps overpressure?

 

Hell no to the stock maps lol. I put in a pretty generous fuel map, no timing map (truck is an alcoholic), and if I'm correct I messed with t he overpressure a bit.

 

Over RPM is at 6000
Overpressure is at 0
Over INJ% is at 90
Fuel pump start pressure PSI is at -1
Fuel pummp run time is at 3
Fuel pump startup time is at 120

 

Did you gradually tune your setup to reach this point, or how did you reach these values? I have a feeling your AIC is fighting your ECU...

 

Everything is where it should be except for Overpressure. Comes 3PSI stock I believe. I set mine to 1 PSI. It tricks the o2 sensor into thinking it’s 14.7 and ramps the AFR up....mine is a little crazy, it jumps to ~12.0 when going into boost for a quick second but then hovers around the 13s......I’m not really sure exactly how it’s supposed to work. As in how it knows how much to enrich the mixture but it deffinetly gives it more gas.



This could be a reason why trims are a bit much. The computer is adding gas via the injectors because the URD box is signaling the ECU that it needs to enrich.

Now here’s where it gets confusing. The 7th instructions say to add fuel using the injector map to cancel positive fuel trims. But it’s not clear if it’s actually referring to the 7th or URDs MAF (different product) box mentioned in the 7th instructions in the same paragraph. If one did not find a commment Gadget made on another forum it would seem that the instructions are referring to the 7th injector map.

On the forum post Gadget explains that a 7th injector is not meant to cancel fuel trims but only meant to add fuel where it leans out. So it almost seems as if it’s not possible to zero fuel trims with the 7th kit. But IDK. It doesn’t seem like anyone does.