Just throwing this out for those with inconsistent startups
08-09-2021, 09:16 PM
#1
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Just throwing this out for those with inconsistent startups
Absolutely no science here.
Like many, I've spent a good bit of time and trouble working on startup settings. These settings will act great for days then might fall flat on a first start attempt a week later. I'd estimate I would have a failed start about every fifteen or so cold starts.
Here is the weird thing. I have a DW200 fuel pump and the original wiring. Since the DW pump went in, I have to replace my main relay about every two or three years. It was last replaced not long after I went from piggyback to MS3. A couple of weeks ago, the relay failed again. I keep an emergency kit in my glove box (main relay, cam sensor, crank sensor). I just popped in the spare relay and was good to go.
Since then, my cold starts have been 100% flawless. I mean great, no doubt about it flawless.
I don't know if there is a connection, but if and when the occasional cold start goes flop again, I'm going to pop in my spare main relay to see if it has any effect on the behavior.
Obviously, YMMV.
Like many, I've spent a good bit of time and trouble working on startup settings. These settings will act great for days then might fall flat on a first start attempt a week later. I'd estimate I would have a failed start about every fifteen or so cold starts.
Here is the weird thing. I have a DW200 fuel pump and the original wiring. Since the DW pump went in, I have to replace my main relay about every two or three years. It was last replaced not long after I went from piggyback to MS3. A couple of weeks ago, the relay failed again. I keep an emergency kit in my glove box (main relay, cam sensor, crank sensor). I just popped in the spare relay and was good to go.
Since then, my cold starts have been 100% flawless. I mean great, no doubt about it flawless.
I don't know if there is a connection, but if and when the occasional cold start goes flop again, I'm going to pop in my spare main relay to see if it has any effect on the behavior.
Obviously, YMMV.
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08-10-2021, 09:56 AM
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I replaced my adjustable FPR when it had issues maintaining a 1:1 rising rate. This had the unexpected result of also fixing a big idle oscillation at startup, as it would take the old FPR longer to get to my set fuel pressure and stabilize it there. So there is a chance, maybe if this particular relay is giving the fuel pump more amperage than the others, that it's helping with start up. Like the others say, take the load off main relay by making it just trigger a second direct to battery relay, and you may even find more benefit.
On a related note, if any one needs an aeromotive compact FPR for cheap, lemme know...
On a related note, if any one needs an aeromotive compact FPR for cheap, lemme know...
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08-14-2021, 07:50 AM
#5
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I appreciate the advice guys. The relays have a lifetime warranty at Advance, so until I happened upon this I was content just swapping them out. The one I removed was installed 6/18/18. It should be interesting when cold weather hits if my cold starts gain consistency as well. I'll pick up one of the Trackspeed kits if they are still available.
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08-14-2021, 11:41 AM
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Grab one of these relay kits:
https://prowireusa.com/p-2266-50-30-...with-base.html
and some of this 12 gage milspec wiring: (double check my work, I’m on my phone:
https://prowireusa.com/c-66-12-awg.html
and some of the same stuff but 16-22 gage for the triggering. You’ll put your current fuel pump wire into either 86 or 85, ground the other. Put a fused 12 gage lead directly from the battery into 30, 87 goes to your fuel pump. You can find diy fuse holder kits on that site too. And then you’ve got a custom fit relay kit with the relay and fuse placed where you want them, and nearly no spliced connections.
https://prowireusa.com/p-2266-50-30-...with-base.html
and some of this 12 gage milspec wiring: (double check my work, I’m on my phone:
https://prowireusa.com/c-66-12-awg.html
and some of the same stuff but 16-22 gage for the triggering. You’ll put your current fuel pump wire into either 86 or 85, ground the other. Put a fused 12 gage lead directly from the battery into 30, 87 goes to your fuel pump. You can find diy fuse holder kits on that site too. And then you’ve got a custom fit relay kit with the relay and fuse placed where you want them, and nearly no spliced connections.
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09-15-2021, 06:08 PM
#8
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I hardwired a new relay for my DW200 fuel pump today. Not a bad job. I'll bump this thread if my random failed start issue reappears.
Thanks for the input, especially Curly with the great links and how-to's.
Thanks for the input, especially Curly with the great links and how-to's.
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11-14-2021, 02:13 AM
#10
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OP, just for info I found a similar thing.
Cold starts have been quite often very sluggish. I was working through fuel, air valve etc and improved it but it was still quite laboured.
My main relay failed, this time sticking slightly on after key off. (on but with high resistance, 12v red white wire at 2V with key off)
Not my first rodeo with the main relay so I started looking on the forums for tips, general consensus was that as the fuel pump is the high current draw through the relay, it is the first port of call to be modified. Many thanks to the hive mind.
I rewired my fuel pump to take the high amperage feed direct from the battery. The main relay now just switches the stock fuel pump and the new relay for the pump. No high current stuff for the pump anymore.
Started the car after the work and literally sprang into life from dead cold. I mean instantly. The best it has ever started, even from hot. This was actually with one of my old main relays back in the car while I wait for the new one to arrive, but my relay was failing to turn off properly, rather than turn on.
Pump is a Walbro 255, which I run at higher pressure (4bar at 1atm).
Early days but the signs so far are good, I'll keep you updated as to if the good starting continues or not.
Difficult to prove the exact science but I would think either giving the pump its own direct feed has given the starter motor and coils a bigger slice of the pie on the stock main feed (I think this, because the starter was definitely cranking faster) or something like voltage correction for my injectors and / or coils isn't set up quite right in my tune. Could be some dirty contacts somewhere in the pump line that are now only expected to transmit low current now possibly too.
Cold starts have been quite often very sluggish. I was working through fuel, air valve etc and improved it but it was still quite laboured.
My main relay failed, this time sticking slightly on after key off. (on but with high resistance, 12v red white wire at 2V with key off)
Not my first rodeo with the main relay so I started looking on the forums for tips, general consensus was that as the fuel pump is the high current draw through the relay, it is the first port of call to be modified. Many thanks to the hive mind.
I rewired my fuel pump to take the high amperage feed direct from the battery. The main relay now just switches the stock fuel pump and the new relay for the pump. No high current stuff for the pump anymore.
Started the car after the work and literally sprang into life from dead cold. I mean instantly. The best it has ever started, even from hot. This was actually with one of my old main relays back in the car while I wait for the new one to arrive, but my relay was failing to turn off properly, rather than turn on.
Pump is a Walbro 255, which I run at higher pressure (4bar at 1atm).
Early days but the signs so far are good, I'll keep you updated as to if the good starting continues or not.
Difficult to prove the exact science but I would think either giving the pump its own direct feed has given the starter motor and coils a bigger slice of the pie on the stock main feed (I think this, because the starter was definitely cranking faster) or something like voltage correction for my injectors and / or coils isn't set up quite right in my tune. Could be some dirty contacts somewhere in the pump line that are now only expected to transmit low current now possibly too.
Last edited by Tchaps; 11-14-2021 at 02:38 AM.
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