Inconsistent startup on street ported 12A

dr.occa · 02-09-2012, 04:05 PM

I've been able to drop in 2 ounces of engine oil down both stacks of the 48 IDA and feather the throttle wheel to get the car to start up but it's never consistent. Sometimes it takes 4 or 5 coaxing attempts and will idle until the gas tank runs dry while other times it'll sputter after multiple tries, idle for a minute then sputter out. Still, after numerous attempts it won't start at all. Is it possible that it's this difficult because of the exhaust setup right now: just a Racing beat header and nothing else after that. Need to get it to the exhaust shop.

Is there a trick to these to where I can just jump in, mash the gas once and then just turn it over?

It's getting to be pretty disappointing. Don't get me wrong. When it fires up, throttle response on it is nuts! Sounds great with that signature gurgling idle.

I've got a March 17th drift event coming up and would love to get the car to it.

Rich@SR · 02-09-2012, 05:37 PM

I don't think the exhaust would cause that to happen but I guess I could be wrong. What else have you changed since it ran well? Could you have removed something and not installed it back correctly when you did the exhaust?

dr.occa · 02-09-2012, 11:30 PM

The Racing Beat Header is all I have. I need to provide more details on this setup.

It's a street ported 12A as I mentioned but it's in an '85 Corolla (rwd of course). I'm running a DLIDFIS setup.

mattallac · 02-10-2012, 01:44 AM

Well first off the dlidfis set up is ok ,lots of coils . Did it run on the dlidfis set up before the carb was installed ?I did a 3 coil set up and it turned out one of my new coils took a shit (pertronics) so I switched to msd and it was all good from there.Did you check your fuel psi and is it going through a regulator at 4 to 4.5 psi ?Also is the fuel pump sucking through a straw or is it free flow (outlet on bottom of tank)? Is it a fuel return system or a dead head system? What fuel pump are you using?Last of all is the carb new or used?

dr.occa · 02-10-2012, 09:39 AM

Quote:

Originally Posted by mattallac

Well first off the dlidfis set up is ok ,lots of coils . Did it run on the dlidfis set up before the carb was installed ?I did a 3 coil set up and it turned out one of my new coils took a shit (pertronics) so I switched to msd and it was all good from there.Did you check your fuel psi and is it going through a regulator at 4 to 4.5 psi ?Also is the fuel pump sucking through a straw or is it free flow (outlet on bottom of tank)? Is it a fuel return system or a dead head system? What fuel pump are you using?Last of all is the carb new or used?

I doubt the previous owner ran an DLIDFIS setup but I couldn't tell you with 100% certainty. All 3 coils are MSD Blaster coils in like new condition. It won't hurt to re-test them just to confirm.

Fuel is via a carter 4070 in the rear to an aeromotive bypass fpr. Line routing is 5/16 incoming to the fpr and a 3/8 bypass return. Pressure readings with just the pump on is 6+psi and that's without the motor running. When I did get it idling on I was able to adjust the pressure down to 4-4.5. I should probably go ahead and just re-run a new 3/8 line from the tank to the fpr just to make sure.

The carb is rebuilt.

mattallac · 02-11-2012, 04:36 AM

Ok well your coils need to be checked for starter , and the specs for your carb are : venturi : 37mm ,Fuel jet no.170 ,air jet no.150,emulsion tube :f-11 and needle valve -no.250 . This is racing beat specs , I have worked with them a lot and for sea level this is a good starting point .RB tends to set the top end of they're tune a little lean ,but a dyno will tell you what you need to add or subtract. Back to your dlidfis :ditch that shit ,use the cap or run DIS . The dlidfis system is a cluster fuck and if it worked that great mazda would have used it to help with its early emission problems. And last of all kill the by pass ,turn it into a dead head system and this will simplify your fuel system ,fuel return systems in carb situations can cause problems ,check your fuel PSI when running .

dr.occa · 02-11-2012, 01:38 PM

Quote:

Originally Posted by mattallac

Ok well your coils need to be checked for starter , and the specs for your carb are : venturi : 37mm ,Fuel jet no.170 ,air jet no.150,emulsion tube :f-11 and needle valve -no.250 . This is racing beat specs , I have worked with them a lot and for sea level this is a good starting point .RB tends to set the top end of they're tune a little lean ,but a dyno will tell you what you need to add or subtract. Back to your dlidfis :ditch that shit ,use the cap or run DIS . The dlidfis system is a cluster fuck and if it worked that great mazda would have used it to help with its early emission problems. And last of all kill the by pass ,turn it into a dead head system and this will simplify your fuel system ,fuel return systems in carb situations can cause problems ,check your fuel PSI when running .

I've already picked up another holley 1-4 psi. It's what I use for my dual side draught set up in my other car and it's always good (knock on wood right).

The DLIDFIS setup is neatly tucked and non-confusing. If anything, I may just go 6AL.

I'm going to go over the IDA jettings just to make sure.

Appreciate ya mattallac

dr.occa · 02-20-2012, 09:10 AM

Here's what I've been trying to describe:

This is after I poured in ~2oz down each barrel.

I've pulled the Aeromotive 13301 (it's for sale in the classified's section) and am about to install the Holley dead head this week. I just have to weld in a 3/8 stainless pick up hard line in place of the "much too small" line that's in the tank.

dr.occa · 03-07-2012, 09:40 PM

Pulled the plugs and spun the motor until it was spitting clean (ok, cleaner).

I found that the trailing plugs were covered in oil and fuel. Upon testing them only one (the plug wire to the front housing trailing) was sparking (very feint) and erratically while the other wasn't sparking at all. I thought it may just be the plugs. I plugged them up to the lead plug wires and they came to life. I confirmed by testing the lead plugs again in their home wires and then on the trailing wires. The same thing occurred with the lead plugs as with the trail plugs on the trailing wires. As soon as I replaced the cap and rotor - BANG! Houston we've got lift off!

THEN, I found that just with the fuel pump going before the car even starts, the pressure on the gauge shoots up to 6 psi! I'm using a Carter 4070 and Holley low press. fpr and 3/8 from tank to pump to fpr and carb (6AN). Looking down the carb I'm also seeing the pump jets dripping (rapidly - more like dribbling) onto the throttle plates. So I'm discovering that it's flooding badly!

I was able to drive it down the street a few hundred yards but when I did an about face it puttered out.

I'll need to inspect the accelerator pump assembly and play (hopefully there's no play) and hopefully a rebuild and float adjustment will fix it.

mattallac · 03-08-2012, 01:02 AM

cool glad to hear you have made some positive progress.

dr.occa · 03-08-2012, 09:48 AM

Thanks, but is it normal for the 4070 to push pass the initial pressure I had set the fpr to? If not, is that indicative of carburetor problems?

02-09-2012, 04:05 PM	#1
dr.occa Rotary Fan in Training Join Date: Mar 2011 iTrader: (2) Posts: 73 Rep Power: 14	Inconsistent startup on street ported 12A I've been able to drop in 2 ounces of engine oil down both stacks of the 48 IDA and feather the throttle wheel to get the car to start up but it's never consistent. Sometimes it takes 4 or 5 coaxing attempts and will idle until the gas tank runs dry while other times it'll sputter after multiple tries, idle for a minute then sputter out. Still, after numerous attempts it won't start at all. Is it possible that it's this difficult because of the exhaust setup right now: just a Racing beat header and nothing else after that. Need to get it to the exhaust shop. Is there a trick to these to where I can just jump in, mash the gas once and then just turn it over? It's getting to be pretty disappointing. Don't get me wrong. When it fires up, throttle response on it is nuts! Sounds great with that signature gurgling idle. I've got a March 17th drift event coming up and would love to get the car to it.

02-11-2012, 04:36 AM	#6
mattallac Rotary Fanatic Join Date: Aug 2011 Location: crockett ca. iTrader: (1) Posts: 176 Rep Power: 0	Ok well your coils need to be checked for starter , and the specs for your carb are : venturi : 37mm ,Fuel jet no.170 ,air jet no.150,emulsion tube :f-11 and needle valve -no.250 . This is racing beat specs , I have worked with them a lot and for sea level this is a good starting point .RB tends to set the top end of they're tune a little lean ,but a dyno will tell you what you need to add or subtract. Back to your dlidfis :ditch that shit ,use the cap or run DIS . The dlidfis system is a cluster fuck and if it worked that great mazda would have used it to help with its early emission problems. And last of all kill the by pass ,turn it into a dead head system and this will simplify your fuel system ,fuel return systems in carb situations can cause problems ,check your fuel PSI when running . Last edited by mattallac; 02-11-2012 at 04:40 AM.. Reason: add

02-20-2012, 09:10 AM	#8
dr.occa Rotary Fan in Training Join Date: Mar 2011 iTrader: (2) Posts: 73 Rep Power: 14	Here's what I've been trying to describe: This is after I poured in ~2oz down each barrel. I've pulled the Aeromotive 13301 (it's for sale in the classified's section) and am about to install the Holley dead head this week. I just have to weld in a 3/8 stainless pick up hard line in place of the "much too small" line that's in the tank. Last edited by dr.occa; 02-20-2012 at 09:12 AM..

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02-09-2012, 05:37 PM	#2
Rich@SR SR Race Engineering Join Date: Jan 2012 Location: Loxahatchee, FL iTrader: (0) Posts: 81 Rep Power: 13	I don't think the exhaust would cause that to happen but I guess I could be wrong. What else have you changed since it ran well? Could you have removed something and not installed it back correctly when you did the exhaust?

02-09-2012, 11:30 PM	#3
dr.occa Rotary Fan in Training Join Date: Mar 2011 iTrader: (2) Posts: 73 Rep Power: 14	The Racing Beat Header is all I have. I need to provide more details on this setup. It's a street ported 12A as I mentioned but it's in an '85 Corolla (rwd of course). I'm running a DLIDFIS setup.

02-10-2012, 01:44 AM	#4
mattallac Rotary Fanatic Join Date: Aug 2011 Location: crockett ca. iTrader: (1) Posts: 176 Rep Power: 0	Well first off the dlidfis set up is ok ,lots of coils . Did it run on the dlidfis set up before the carb was installed ?I did a 3 coil set up and it turned out one of my new coils took a shit (pertronics) so I switched to msd and it was all good from there.Did you check your fuel psi and is it going through a regulator at 4 to 4.5 psi ?Also is the fuel pump sucking through a straw or is it free flow (outlet on bottom of tank)? Is it a fuel return system or a dead head system? What fuel pump are you using?Last of all is the carb new or used?

03-07-2012, 09:40 PM	#9
dr.occa Rotary Fan in Training Join Date: Mar 2011 iTrader: (2) Posts: 73 Rep Power: 14	Pulled the plugs and spun the motor until it was spitting clean (ok, cleaner). I found that the trailing plugs were covered in oil and fuel. Upon testing them only one (the plug wire to the front housing trailing) was sparking (very feint) and erratically while the other wasn't sparking at all. I thought it may just be the plugs. I plugged them up to the lead plug wires and they came to life. I confirmed by testing the lead plugs again in their home wires and then on the trailing wires. The same thing occurred with the lead plugs as with the trail plugs on the trailing wires. As soon as I replaced the cap and rotor - BANG! Houston we've got lift off! THEN, I found that just with the fuel pump going before the car even starts, the pressure on the gauge shoots up to 6 psi! I'm using a Carter 4070 and Holley low press. fpr and 3/8 from tank to pump to fpr and carb (6AN). Looking down the carb I'm also seeing the pump jets dripping (rapidly - more like dribbling) onto the throttle plates. So I'm discovering that it's flooding badly! I was able to drive it down the street a few hundred yards but when I did an about face it puttered out. I'll need to inspect the accelerator pump assembly and play (hopefully there's no play) and hopefully a rebuild and float adjustment will fix it.

03-08-2012, 01:02 AM	#10
mattallac Rotary Fanatic Join Date: Aug 2011 Location: crockett ca. iTrader: (1) Posts: 176 Rep Power: 0	cool glad to hear you have made some positive progress.

03-08-2012, 09:48 AM	#11
dr.occa Rotary Fan in Training Join Date: Mar 2011 iTrader: (2) Posts: 73 Rep Power: 14	Thanks, but is it normal for the 4070 to push pass the initial pressure I had set the fpr to? If not, is that indicative of carburetor problems?