How long should it take to pump one gallon of fuel from the fuel rail with a Walbro 307? It took mine 52 seconds. The reason I'm asking is because I've developed a pop through the intake under boost. Seems like I have plenty of pressure but maybe not enough volume. On directscan when this happens, I will get a crazy low o2 reading for 1 or 2 frames such as 190 or 482 or 680! Any ideas? Thanks, R.B.
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How Lomg To pump?
- Thread starter rb68rr
- Start date
The Machine
Not broke? Try harder!
- Joined
- Sep 7, 2005
I can't answer this question as asked, but I think I can contribute none the less.
When my car surges or bucks slightly in higher rpms, I get a weird WOT reading from my Scanmaster like 320mv & 9.9kr or 45 & .3. There is a gremlin under the hood somewhere that I haven't found as of yet.
Anyway, I think it's possible that at certain times during an issue, WOT readings can be way off. I wish someone could confirm that.
Good Luck!
When my car surges or bucks slightly in higher rpms, I get a weird WOT reading from my Scanmaster like 320mv & 9.9kr or 45 & .3. There is a gremlin under the hood somewhere that I haven't found as of yet.
Anyway, I think it's possible that at certain times during an issue, WOT readings can be way off. I wish someone could confirm that.
Good Luck!
jurassic five 7
Active Member
- Joined
- Apr 6, 2005
I belive it's something like drain 5 gallons in 30 seconds is the right calculations.
http://www.autoperformanceengineering.com/ posts Walbro pump data. Click the "technical" link and scroll down.
Assuming 12 volts at the pump (car at idle), pressure at 40 psi (about right for a car at idle), then look under the "255 liter" column -- this is the Walbro 307.
It will flow 58 gal/hr, which is about 1 gallon per minute.
rb68rr - your 307 pump seems about "normal", for a car at idle.
Assuming 12 volts at the pump (car at idle), pressure at 40 psi (about right for a car at idle), then look under the "255 liter" column -- this is the Walbro 307.
It will flow 58 gal/hr, which is about 1 gallon per minute.
rb68rr - your 307 pump seems about "normal", for a car at idle.
OK, so what's causing the low 02 reading for a frame or two and the pop? Swapped coil and ignition module with a known good one. Plugs are only a month old. Wires are good. New fuel filter. This happened before about a month ago and all I did to fix it was to raise the fuel pressure a couple of pounds. I was at 45 psi and raised it to 48 psi which already seems to high. Raised it to 50 psi and still got the pop! BTW, even at this high pressure the 02's are still at 780-790mv at wot! Somethings not right. R.B.
BTW, this pump is 6 years old!
BTW, this pump is 6 years old!
OK, so what's causing the low 02 reading for a frame or two and the pop? Swapped coil and ignition module with a known good one. Plugs are only a month old. Wires are good. New fuel filter. This happened before about a month ago and all I did to fix it was to raise the fuel pressure a couple of pounds. I was at 45 psi and raised it to 48 psi which already seems to high. Raised it to 50 psi and still got the pop! BTW, even at this high pressure the 02's are still at 780-790mv at wot! Somethings not right. R.B.
BTW, this pump is 6 years old!
Well, without any direct scan data to look at it would be impossible to tell. Besides that, keep in mind that any fuel pressure adjustments you make are just going to be erased by the BLM in the chip. That's what it does, sees an A/F ratio change because of the fuel pressure adjustment and then changes the BLM to compensate and nullify the adjustment.
If the pressure is ok at WOT under boost, which means 1:1 for boost pressure to fp increase then its not the pump. If you have a volume problem then you will have a pressure problem when the engine is using fuel faster than the pump can replenish the rail. I would suspect a chip problem or a bad O2 sensor. Ive seen them throw out garbage numbers when they start to get a little fouled. Be sure you have enough voltage at WOT also. So whats the fuel presusre under boost? Fp at idle means nothing if the pump is shot and cant keep the rail at the proper pressure. Check your voltage at the pump also, not just the battery voltage.
I haven't checked the wot fuel pressure this time yet. But when this happened a month ago I did. I was running 45psi static and 16 lbs of boost and it showed 61-62 lbs. Now when I got the cough or pop the fuel pressure needle would jump. As long as i don't get a pop the wot fuel pressure shows good. R.B.
The Machine
Not broke? Try harder!
- Joined
- Sep 7, 2005
Now the question is did it jump because it popped, or did it pop because it jumped?
Now the question is did it jump because it popped, or did it pop because it jumped?
Very likely. That is, it jumped because of the pop. Those types of backfires usually wreak havoc with the manifold vacuum/pressure which directly affects indicated fuel pressure directly.
When trying to diagnose a cough or intake pop using Directscan, what do you look for to try and determine if it's ignition related or fuel related? The only thing I can see is that the 02's drop into the 600's for a frame or two and the rpm's drop about 400 rpm's. R.B.
When trying to diagnose a cough or intake pop using Directscan, what do you look for to try and determine if it's ignition related or fuel related? The only thing I can see is that the 02's drop into the 600's for a frame or two and the rpm's drop about 400 rpm's. R.B.
Does it seem to be effected more by boost or rpm or both? Maybe a valve is hanging open a little. What is your BLM at WOT? If its at 128 then the only thing that will change WOT fuel is an increase or decrease in fuel pressure.
When trying to diagnose a cough or intake pop using Directscan, what do you look for to try and determine if it's ignition related or fuel related? The only thing I can see is that the 02's drop into the 600's for a frame or two and the rpm's drop about 400 rpm's. R.B.
You could be seeing MAF resets. Very common when the MAF hits it's 255 limit, the MAF buffer overflows and resets. More often than not it'll cause the symptoms you're describing, but again, without the file to look at, I'm guessing again.
bison, it seems to be both. The chip locks the blm at 128 at wot.
TurboDave, I would love to send you the files but I'm on this stupid Webtv and it can't happen. But it will cough and pop before the maf ever reaches 255 sometimes. Right now I have the boost turned back to 15 psi, running 48psi of fuel pressure and my 02's are at 790 wot! I don't believe I could get the 02's over 800 running 55psi of fuel pressure! R.B.
TurboDave, I would love to send you the files but I'm on this stupid Webtv and it can't happen. But it will cough and pop before the maf ever reaches 255 sometimes. Right now I have the boost turned back to 15 psi, running 48psi of fuel pressure and my 02's are at 790 wot! I don't believe I could get the 02's over 800 running 55psi of fuel pressure! R.B.
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