I was thinking the same thing. I'm overdue for a new filter and this has started happening to my car.
Fuel pump not priming - car slow to start - why?
- Thread starter eddyvr4
- Start date
- Location
- Melbourne
- First Name
- Ed
- Drive
- 2000 Legnum VR4 Manual, Ford Territory family runabout, BMW K1300R.
Personally that seems backwards to me. A clogged filter should exhibit problems as the engine tries to draw more through it than the restriction allows, not when the car starts.
Okay, firstly I wanna say I really appreciate all the info in this thread. It has prevented me from trying alot of things done here which were theories I had in mind too. So thats for that. I've had this slow start problem for about a year now and it's annoying, embarrassing and not to mention it cuts the lifespan of your starter. After going through this thread in depth I was left at the Maf and fuel pressure. My Maf checked out fine so that left me at fuel pressure...FPR checked out fine which lead me to the o'ring in the fuel pump assembly. Did a search for alternatives and found something on an eclipse forum... Needless to say...it worked! Seriously... Ditch the o'ring and spacer and get this part. Its a Toyota part... Part # 23239-21010. My car starts immediately now. So if u had this issue. U can try this. I've attached a pic comparing our o'ring and spacer and the seal from Toyota. Fits tight and snug. Put a little lube on it tho as it is very tight.
naughtika
OzVR4 Stalker
thanks for the info, may have to try this 
Doubt anyone is around still but I've read this whole thread and I'm still at a loss on a start up issues once warmed up.
140k on the clock, new Denso plugs, new fuel pump sealing sleeve, new O ring on ISC, removed and bench tested hot start solenoid, no vacuum leaks, no boost pipe leaks.
The only thing I can't remember is if the FP dropped to zero over time or within seconds.
Not sure how to check the second fuel sender seal or connecting hose for air or fuel leaks.
Fuel consumption has gone from 12L/100 to about 16 in the last few weeks.
It's more annoying than anything else, parked for a short time anywhere and needs 3 secs at least to start, other than first off in the morning.
At 24 years old it could be so many things.
140k on the clock, new Denso plugs, new fuel pump sealing sleeve, new O ring on ISC, removed and bench tested hot start solenoid, no vacuum leaks, no boost pipe leaks.
The only thing I can't remember is if the FP dropped to zero over time or within seconds.
Not sure how to check the second fuel sender seal or connecting hose for air or fuel leaks.
Fuel consumption has gone from 12L/100 to about 16 in the last few weeks.
It's more annoying than anything else, parked for a short time anywhere and needs 3 secs at least to start, other than first off in the morning.
At 24 years old it could be so many things.
Tony_T
Leaving Skid Marks
This may be a total red herring but check the relay on the engine side of the firewall, the one which switches the resistor in or out of the circuit to the fuel pump. I had one fail and I found it was a really tiny cheap Chinese relay fitted inside what looked like a genuine Mitsi housing. Bad contact in this relay will starve the pump of voltage at times, but not all of the time.
Sorry if I'm way off with this, but it's worth checking for reassurance.
Sorry if I'm way off with this, but it's worth checking for reassurance.
Gotta say, you could be right! I did consider this and ordered a new relay from the US believe it or not. Maybe a week away still, RY291 part no.
I did have a go at cleaning the contacts as they were pitted, problem is being a coil it's susceptibility to changes in values based on temperature and age.
Have also got an NTK O2 sensor coming to hopefully sort out the fuel consumption.
Ordered a Aeromotive 340lph fuel pump as the Deatschwerks is probably on the way out too.
If all that fails I'll be looking for an old priest and a younger one!
I did have a go at cleaning the contacts as they were pitted, problem is being a coil it's susceptibility to changes in values based on temperature and age.
Have also got an NTK O2 sensor coming to hopefully sort out the fuel consumption.
Ordered a Aeromotive 340lph fuel pump as the Deatschwerks is probably on the way out too.
If all that fails I'll be looking for an old priest and a younger one!
Tony_T
Leaving Skid Marks
Ah now you've thrown another thing in the mix.
First, I just used a standard changeover type automotive relay and replaced the connector: very cheap, available most anywhere and far more robust than the original "Mitsi' Chinese one.
BUT now you've said you have a non-stock fuel pump so the value of the resistor will not be correct for what you have unless by sheer chance it happens to draw the exact same amount of current as the original, unlikely. Bridging out the resistor totally as some folks advocate will cause the fuel pressure regulator to be unable to cope when the injector duty cycle is low (demand is low) so then you'll have another problem. BTW the actual fuel pump on/off relay is behind the stereo right at the back, the firewall one only controls whether the resistor is in circuit or not. Once you have that Aeromotive pump installed you'll need to check the fuel pressure in both modes and find a resistor that allows the correct pressure at low demand, unless you're using an aftermarket FPR in which case you likely won't need the resistor and relay at all, just wire it together.
First, I just used a standard changeover type automotive relay and replaced the connector: very cheap, available most anywhere and far more robust than the original "Mitsi' Chinese one.
BUT now you've said you have a non-stock fuel pump so the value of the resistor will not be correct for what you have unless by sheer chance it happens to draw the exact same amount of current as the original, unlikely. Bridging out the resistor totally as some folks advocate will cause the fuel pressure regulator to be unable to cope when the injector duty cycle is low (demand is low) so then you'll have another problem. BTW the actual fuel pump on/off relay is behind the stereo right at the back, the firewall one only controls whether the resistor is in circuit or not. Once you have that Aeromotive pump installed you'll need to check the fuel pressure in both modes and find a resistor that allows the correct pressure at low demand, unless you're using an aftermarket FPR in which case you likely won't need the resistor and relay at all, just wire it together.
Thanks for all that.
The relay is a Chrysler/Dodge equivalent using the Mitsi part number.
Runing a Tomei FPR and yes if the relay isn't suitable I'll just bridge the resistor and run battery voltage constantly.
I'll post an update when the new fuel pump or relay go in.
Well that didn't go well, the new relay cooked itself within 5 seconds of powering up.
I have left the new fuel pump out of the equation for now as with a wideband kit.
Running a loaner ecu from TME Steve while mine gets a remote tune.
Not convinced we really need a dual speed set up as a good FPR should do it's job basically sending back most of the fuel in the system while maintaining correct pressure at the injectors.
Took a few voltage readings and found 8.5 VDC powering the fuel pump at idle so a sizeable voltage drop of 5 VDC across the resistor.
Didn't quite think it through with the fuel pump, hoping the flow isn't too much for the FPR and injectors!
I have left the new fuel pump out of the equation for now as with a wideband kit.
Running a loaner ecu from TME Steve while mine gets a remote tune.
Not convinced we really need a dual speed set up as a good FPR should do it's job basically sending back most of the fuel in the system while maintaining correct pressure at the injectors.
Took a few voltage readings and found 8.5 VDC powering the fuel pump at idle so a sizeable voltage drop of 5 VDC across the resistor.
Didn't quite think it through with the fuel pump, hoping the flow isn't too much for the FPR and injectors!
Tony_T
Leaving Skid Marks
Wow the relay cooked? Open it up and see what's inside!
As I said mine was a junk Chinese PCB mounted relay on a tiny board and fitted very convincingly in a genuine looking automotive relay housing (those Chinese are clever). I'm surprised it lasted as long as it did but it let me down seriously when driving a couple of times which could have been disastrous if someone had been following me a bit close as the car simply stopped dead and refused to restart until left for a while. I found what it was purely by chance.
You said you have an aftermarket FPR so you most likely don't need the reduced fuel pressure that the resistor gave even with the uprated pump, but do keep something connected in place of the relay coil as the ECU will be monitoring the relay coil for continuity and will throw an error if it doesn't see something there.
Just a thought, is the fuel return adequate to return the volume of fuel being pumped but not needed? It may not be solely a FPR restriction.
As I said mine was a junk Chinese PCB mounted relay on a tiny board and fitted very convincingly in a genuine looking automotive relay housing (those Chinese are clever). I'm surprised it lasted as long as it did but it let me down seriously when driving a couple of times which could have been disastrous if someone had been following me a bit close as the car simply stopped dead and refused to restart until left for a while. I found what it was purely by chance.
You said you have an aftermarket FPR so you most likely don't need the reduced fuel pressure that the resistor gave even with the uprated pump, but do keep something connected in place of the relay coil as the ECU will be monitoring the relay coil for continuity and will throw an error if it doesn't see something there.
Just a thought, is the fuel return adequate to return the volume of fuel being pumped but not needed? It may not be solely a FPR restriction.
Thanks Tony. Twas a shocking piece of chinesium inside, the coil cooked within seconds, cheap and nasty.
It's running a DW200 for now but about 4 years old at least, once power is off fp drops to zero almost instantly.
Fuel lines are mostly original other than a new portion from the FPR to fuel rail.
Fuel pressure gauge sits rock steady and rises evenly with throttle opening.
Steve from TME feels the FPR will handle the new 340 fuel pump though he will be making changes in the tune to accommodate.
I think I'll basically negate the resistor by bridging the 2 ends, hopefully providing 12volts and above at all times.
It's cold as balls in Melbourne ATM and not looking do anything outdoors till say Monday, don't think open fuel tanks are a good idea in a garage attached to the house.
It's running a DW200 for now but about 4 years old at least, once power is off fp drops to zero almost instantly.
Fuel lines are mostly original other than a new portion from the FPR to fuel rail.
Fuel pressure gauge sits rock steady and rises evenly with throttle opening.
Steve from TME feels the FPR will handle the new 340 fuel pump though he will be making changes in the tune to accommodate.
I think I'll basically negate the resistor by bridging the 2 ends, hopefully providing 12volts and above at all times.
It's cold as balls in Melbourne ATM and not looking do anything outdoors till say Monday, don't think open fuel tanks are a good idea in a garage attached to the house.
Tony_T
Leaving Skid Marks
I thought as much. It's getting that you can't trust much of anything these days as everything is made in China to the very lowest standard possible.
With what you're having done I'd say that you'll be fine to just bypass that relay / resistor combination and if you leave your old relay if you still have it connected to the coil wires the ECU will be happy, otherwise a 1 watt resistor of something like 1k ohms would do fine and take up a lot less space.
With what you're having done I'd say that you'll be fine to just bypass that relay / resistor combination and if you leave your old relay if you still have it connected to the coil wires the ECU will be happy, otherwise a 1 watt resistor of something like 1k ohms would do fine and take up a lot less space.
Much appreciated mate.
Installed the new fuel pump earlier and so far so good.
I'll see it goes after a drive and a brief stop. Slightly longer pressure hold on switch off than before but still drops away after a few seconds.
Got caught up with family so no resistor bypass I'll do that tomorrow
Installed the new fuel pump earlier and so far so good.
I'll see it goes after a drive and a brief stop. Slightly longer pressure hold on switch off than before but still drops away after a few seconds.
Got caught up with family so no resistor bypass I'll do that tomorrow
Tony_T
Leaving Skid Marks
Did you put your old relay back in then?
Old relay in to keep the ECU happy, FPR gauge was off its rocker as I assumed the supply voltage.of 7.5 wasn't enough at idle and the needle was bouncing between 40 and 42 psi.
Bypassed the resistor and the gauge hit 50 psi rock steady.
Dropped it down to 42 took it for a squirt and felt noice.
Tomorrow or the next day I'll instal and AEM wideband gauge and tig in a second bung for the sensor.
Does anyone know when the dual speed relay kicks in to run battery voltage?
Is it boost related or RPM controlled?
Bypassed the resistor and the gauge hit 50 psi rock steady.
Dropped it down to 42 took it for a squirt and felt noice.
Tomorrow or the next day I'll instal and AEM wideband gauge and tig in a second bung for the sensor.
Does anyone know when the dual speed relay kicks in to run battery voltage?
Is it boost related or RPM controlled?
Tony_T
Leaving Skid Marks
No idea, I guess the ECU figures out when the injector duty cycle will get past some point assuming factory FPR control and switches it then.
You could connect a LED with suitable series resistor (680 ohms is a good value) in parallel with the relay coil, bring it out and duct tape it to the windscreen where you can see it from your driving position then observe its behaviour over a few days of driving although if it is in any way related to air / fuel ratio as well the lack of change in fuel pressure with the relay bypassed may confuse it a bit. At least you'd get some idea of it though. I can't remember if the coil is energised for full voltage or if it comes on to bring in the resistor, you'd soon see.
After you said the new relay fried I was a little concerned that the ECU's output that drives the coil could have been damaged but you'd have had an error by now if it was so you were lucky or the circuit has very good current limiting protection.
You could connect a LED with suitable series resistor (680 ohms is a good value) in parallel with the relay coil, bring it out and duct tape it to the windscreen where you can see it from your driving position then observe its behaviour over a few days of driving although if it is in any way related to air / fuel ratio as well the lack of change in fuel pressure with the relay bypassed may confuse it a bit. At least you'd get some idea of it though. I can't remember if the coil is energised for full voltage or if it comes on to bring in the resistor, you'd soon see.
After you said the new relay fried I was a little concerned that the ECU's output that drives the coil could have been damaged but you'd have had an error by now if it was so you were lucky or the circuit has very good current limiting protection.
I had the park brake off and was watching through the bonnet when I first tried it.
It cooked quickly with smoke coming out the sides.
I've bypassed the resistor now and it's been starting fine with steady pressure, needle not bouncing anymore.
Slightly off topic, my interpretation of setting the APS senor for auto with TCL may have been wrong. At idle I believe the APS should show continuity with a .5mm feeler gauge between throttle plates.
Pretty sure the write ups state find continuity and then go to just where it goes open.
It's all white man's magic to me!
It cooked quickly with smoke coming out the sides.
I've bypassed the resistor now and it's been starting fine with steady pressure, needle not bouncing anymore.
Slightly off topic, my interpretation of setting the APS senor for auto with TCL may have been wrong. At idle I believe the APS should show continuity with a .5mm feeler gauge between throttle plates.
Pretty sure the write ups state find continuity and then go to just where it goes open.
It's all white man's magic to me!
- Location
- SA
- First Name
- Bill
- Drive
- 2000 Galant Type-V
1997 Triton GLS [6G74 conversion]
2019 i30 N-Line
If i get a chance, ill have a look at the code. Theres a few conditions that need to be met before switching to full voltage.
I hex edited my rom to be full voltage all the time just to test, instead of ripping it out.
You can log the fuel pump speed in evoscan if you want to see when it changes, can get the PID to query.
Also, ecu doesnt care if the resistor is completely missing, so no need for a dummy resistor, etc
I hex edited my rom to be full voltage all the time just to test, instead of ripping it out.
You can log the fuel pump speed in evoscan if you want to see when it changes, can get the PID to query.
Also, ecu doesnt care if the resistor is completely missing, so no need for a dummy resistor, etc
Thanks for your reply. I have a cable but it went Gladys on me so waiting on one that has somehow been sitting in AusPost since last Sunday.
For now it has a nice idle and doesn't stink like it used to.
Really looking forward to checking the APS and TPS through Evoscan.
Didn't expect to see 7.5 Vdc as the output. I'm guessing that and a poor sealing O ring on the pump have stumped a few of us over the years.
