Is this a 13mm pump thing???

P

PRattenbury

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Jan 28, 2007
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My truck, when running at highway speeds, flatly must start sputtering like it's running out of fuel when under low-to-no-load conditions. It's perfectly happy if it's got a load on it. It's about to drive me bat-chit. I replaced the brake light switch, the TPS, checked the voltage (and increased) on the TPS, added a click to the 4KGSK, changed to a CDS 5KGSK, nothing helps! Am I missing something else that may be the cause? I guess it's obvious I am, but what? If it isn't governor bounce, and it's not a TPS or lockup issue, what the F else can it be? AAAAAARRRRRGGGGHHHHH!!!!!
 
What do you have your timing set at Paul?...24* IIRC? When you are coasting and barely touch the pedal do you get the timing rat,rat,rat,rat noise? Blue smoke can also mean retarded timing. Your motor is fresh so you can rule out any major piston, valve issues. These 13mm pumps are not the most street friendly pumps to begin with. With my timing set at 30* my truck runs real good, but smokes white big time (like a pulling truck) at idle, especially when in gear. At 30* the rat,rat noise is more pronounced. I have mine set at 22* now and the white idle smoke has disappeared. I still get the timing noise, but not as much. You should play with the timing a bit. I have a timing tool that I use which makes timing real easy. Pm me if you want one, they are custom made.
 
Glad I'm not the only one with this. I brought mine home saturday towing a 24ft trailer w/ car on it. Going through town at low speed barely touching the throttle it sounds like it's running on 4cyls. I'm at 8.5mm lift timing(around 25deg). Hard to start too.
 
Yep, 24 degrees. I thought about taking a little timing out just because it's so loud in the first place. I was advised against it because I also have a degreed cam, and things can go wacky real quick.
 
PRattenbury said:
Haven't noticed. I'll pay attention next time. Wouldn't that mean engine oil?
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I don't think it's engine oil, I think it's fueling the wrong point of the cylinder stroke. Either too early for that RPM or too lightly(too little) to match the timing for that RPM.
 
PRattenbury said:
Yep, 24 degrees. I thought about taking a little timing out just because it's so loud in the first place. I was advised against it because I also have a degreed cam, and things can go wacky real quick.
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The pump timing has zero effect on the piston to valve clearances. What size injectors are you running?
 
Glad I have no problems with my 13mm CDS pump. Timing is 18*pump and run 5x18's on the street. Starts better then stock.
 
Texas Cowboy said:
Glad I have no problems with my 13mm CDS pump. Timing is 18*pump and run 5x18's on the street. Starts better then stock.
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I have no problems with mine (knock on wood), but I did. It all boiled down to pump timing. At 30* is was supplying too much fuel too early (like Joe explained above). When idling I had loads of white smoke and it would turn blue at times. I believe my blueish smoke was from washing down the cylinders while at idle. Bring the rpm's up and the truck flat out rocked!! I had to lower timing to 22* so it would have some street manners and not leave a white cloud of smoke at stop lights. I'm racing next weekend and debating on whether to turn up timing or not. What do ya think?????
 
Mine was originally set to 30*pump. Me and MAXTORQ had some isues getting it started. Set pump back to CDS and they retimed it to 18* pump and all has been good since. Fuels like mad!! But with some AFC tuning it is not to smokey. The 5x18's cause haze pretty much all the time though. Mine also blows a little white/blueish smoke before warmed up. But his is due to lower compression and injectors mostly.
 
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