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This is like the never ending story. I was 99% certain the issue was resolved. Today out of curiosity since I was working on the car parked next to it I started the car and let it run for a while. At the 10 minute mark the fans kicked on and the fuel pressure dropped and the AFR began to rise to low 16's. The rim was on so I couldn't quickly check the voltage at the pump. I shut the car off then removed the tire. Turned the key and the pump sounded loud and dry as it primed. I cycled the key 3 times and the pressure was good and the pump sounded normal. Started the car and everything was back in spec. I turned every accessory on and the voltage stayed at 12.9 at idle and everything was still in spec. Ran for another 10 minutes and everything was fine.
The car has about 1/2 a tank of fuel which is approximately 9 gallons.
The only 2 culprits I've thought about were pump voltage and pump canister being low on fuel. I'm out of suggestions. Seems like the initial voltage hit from the fans triggers the phenomenon
Does anyone know if I can fabricate a bracket to hold a walbro 450 pump to the sending unit and eliminate the white plastic bucket ? Maybe just use the walbro pump and filter ? No bucket or sock ? Just looking for ideas to be certain the pump has enough fuel at all times .
12.9v at idle with a rewired pump doesnt sound too good. you lose additional voltage throught the thin wires from the plug. run the ground to the battery or alternator. o.k., maybe it goes to 14.5 if you idle it at 2000 rpm?
Here's a question...... Is the fuel pump and fans on the same circuit? I've got twin spal fans on the factory wiring. It seems like the common denominator is the fans kicking on and the voltage dropping. Could the aftermarket fans be pulling too much voltage with the aftermarket pump if they are both on the same circuit?
I'll add a redundant ground to the pump harness. Maybe even pull power from the alternator to the fans so when the fans kick on they're not robbing power from the pump.
The entire point of the hotwire kit is to give the pump it's dedicated power source. The only thing you are running through the computer is the trigger to the relay to power the pump on.
Might be worth checking the power at the fuse box during that 'fan' time as well, could very well be a grounding issue.
I started the car today to let it run checking for lean condition and after 5 minutes the lean conditions came back, even before the fans kicked on. The voltage at the pump was 13.45 at idle which makes me think the canister is getting sucked down to low. It's got a 1/2 tank of gas and I can't believe the canister isn't completely full of fuel. I'm about to Swiss cheese that canister tomorrow when it's not as humid. If that doesn't work I'm pretty much left with ordering a drop in pump canister kit .
Last night when it cooled off I cut about a dozen three-quarter inch holes in the canister. Ran the car for about 25 minutes and everything was running well. I tested the voltage at the pump right away and it was at 13.4. After the accessories started to turn on the voltage dropped to 12.4 and everything was still in spec. Seems like the holes I put in the canister might have been the solution. I'm still going to do some work to the grounds.
I upgraded the ground in the canister from the pump to the sending unit. Later I'm going to ground outer portion of the sending unit to the frame. Im looking for a braided ground strap.
Last night when it cooled off I cut about a dozen three-quarter inch holes in the canister. Ran the car for about 25 minutes and everything was running well. I tested the voltage at the pump right away and it was at 13.4. After the accessories started to turn on the voltage dropped to 12.4 and everything was still in spec. Seems like the holes I put in the canister might have been the solution. I'm still going to do some work to the grounds.
I upgraded the ground in the canister from the pump to the sending unit. Later I'm going to ground outer portion of the sending unit to the frame. Im looking for a braided ground strap.
Isn't there 2 right around there? I think one is by the filler and the other is by where the factory fuel filter goes
Isn't there 2 right around there? I think one is by the filler and the other is by where the factory fuel filter goes
Probably. There isn't any kind of ground on the sending unit which is where the pump ground goes to. With the fuel tank being plastic, I don't see how the sending unit would get ground through the plastic tank. I attached a 10 gauge wire from a sending unit bolt to self tapper in the frame. Maybe it does something, maybe it does nothing, but it makes me feel a little better knowing that the pump is grounded better .
Tonight I cut the entire bottom out of the canister and pitched the factory sock. Now I'm just using the walbro pump and the filter that comes with the pump. I'm still having the same issue. Fuel pressure goes down, AFR goes up, and the pump sounds dry making a loud noise consistent with the noise a fuel pump makes the very 1st time you turn the key on.
The only thing I can think of now is I've got a bad pump or the fuel supply line from the pump to the sending unit is collapsing and restricting fuel flow.
i would take the pump out and check everything on the bench (outside) incl. regulator using a bucket full of gas. im sure you can use rubber hose to connect it.
btw, could you confirm for me what the connections at the fuel hat are? black (bottom)= pump out? blue (middle) return from reg.? green (top) return from right tank/siphon pump? thanks.
I'm still thinking you have a voltage issue here, your dropping over a full volt. what is the voltage at the alternator during all this? you mentioned you have SPAL fans and such, could it be that you may need to bump up to a higher amp alternator?
I don't want you throwing parts at this, but sounds you isolated the issue to the voltage dropping. The hot wire kit will solve the issue with the power drawl, but if the entire car is having a voltage issue, you may need to focus on that.
I'm still thinking you have a voltage issue here, your dropping over a full volt. what is the voltage at the alternator during all this? you mentioned you have SPAL fans and such, could it be that you may need to bump up to a higher amp alternator?
I don't want you throwing parts at this, but sounds you isolated the issue to the voltage dropping. The hot wire kit will solve the issue with the power drawl, but if the entire car is having a voltage issue, you may need to focus on that.
The voltage at start up at the alternator is 14.7.
The voltage at start up at the fuse box is 14.6.
The voltage at the pump is 14.12.
The voltage at the pump when the issue occurs is 14.28, strange how the pump has more voltage during the issue. Maybe because it's not working as hard because it's dry?
I took a short video of what the pump sounds like when I try to re-start the car. It takes half a dozen key cycles to prime it then it will hold a pressure and started right up with proper pressure and air fuel ratio.
i would take the pump out and check everything on the bench (outside) incl. regulator using a bucket full of gas. im sure you can use rubber hose to connect it.
btw, could you confirm for me what the connections at the fuel hat are? black (bottom)= pump out? blue (middle) return from reg.? green (top) return from right tank/siphon pump? thanks.
Looks like the bottom line marked black goes into the fuel pump. The top line marked green goes about an inch into the top of the sending unit and the middle marked blue goes in the top of the canister.
Since the guys at Walbro seem to be taking extra extra long lunches today, I got bored and now I'm running the pump in a bucket of fuel. The voltage from this battery isn't as high as the car parts out but the pump has been running for over 10 minutes and hasn't changed tone.
PS. My big battery charger broke last week and I left it at the race track so all I have is this battery tender.
07-07-2017, 06:38 PM
