leaking EFI injector
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
I don't know for sure but I believe they can dribble fuel by after shutdown if they're worn or dirty. If that's true, you'd have a flooded cylinder and associated.
If your fuel rail is supposed to stay pressurized when you shut down wouldn't it show a pressure loss? You might also have a weak firing cylinder once it starts. Just guessing a little.
If your fuel rail is supposed to stay pressurized when you shut down wouldn't it show a pressure loss? You might also have a weak firing cylinder once it starts. Just guessing a little.
Burning Brakes
Joined: Dec 2004
Posts: 800
Likes: 3
From: Idaho
I would think that if it were severe enough you might have a dieseling condition after shut down, rich fuel smell from exhaust, poor mileage and a hard start like the engine was flooded. I have the Ram Jet service manual with trouble shooting tips. If you discribe your symptoms I will look them up and get back to you with some recommended fixes.
Good luck
Russ
Good luck
Russ
Thread Starter
Race Director
Joined: Jun 2006
Posts: 17,901
Likes: 751
From: Inverness FL
St. Jude Donor '07
I would think that if it were severe enough you might have a dieseling condition after shut down, rich fuel smell from exhaust, poor mileage and a hard start like the engine was flooded. I have the Ram Jet service manual with trouble shooting tips. If you discribe your symptoms I will look them up and get back to you with some recommended fixes.
Good luck
Russ
Good luck
Russ
thanks...
i'm having hard starts when the engine is hot, and a kind of 'grunt' as it turns over while trying to start that would remind one of an 'almost hydrostatic lock'. could be getting too much gas while hot cranking rather than a leaking injector....
Bill
Burning Brakes
Joined: Dec 2004
Posts: 800
Likes: 3
From: Idaho
Bill
I checked your profile and it does not mention what type of injection you have, so if your's has modern sensors here's what the Ram Jet manual suggests to check.
1. OBD check, any codes set ?
2. Check for correct base timing.
3. Check for proper operation of fuel pump relay circuit.
4. Check for proper fuel pressure.
5. Check for proper ignition voltage output.
6. Check for a ECT(engine coolant temp) sensor shifted in value.
7. Check MAP (Manifold absolute pressure) sensor for opens or shorts
to ground.
8. Check for proper operation of the TP (Throttle position) sensor.
9. Check for proper operation of the IAC (Idle air control) valve.
I realize that these are genric checks but the process for completing these checks are outlined in the manual.
I would also check your starter. I had a similar problem with my car, started fine but was slow to crank when hot. (mini starter) Turns out that one of the bridge wires on the brushes had broken and was making limited contact.
Good luck
Russ
ps. PM me with your ph. # and I'll walk you thru the diagnostic process.
I checked your profile and it does not mention what type of injection you have, so if your's has modern sensors here's what the Ram Jet manual suggests to check.
1. OBD check, any codes set ?
2. Check for correct base timing.
3. Check for proper operation of fuel pump relay circuit.
4. Check for proper fuel pressure.
5. Check for proper ignition voltage output.
6. Check for a ECT(engine coolant temp) sensor shifted in value.
7. Check MAP (Manifold absolute pressure) sensor for opens or shorts
to ground.
8. Check for proper operation of the TP (Throttle position) sensor.
9. Check for proper operation of the IAC (Idle air control) valve.
I realize that these are genric checks but the process for completing these checks are outlined in the manual.
I would also check your starter. I had a similar problem with my car, started fine but was slow to crank when hot. (mini starter) Turns out that one of the bridge wires on the brushes had broken and was making limited contact.
Good luck
Russ
ps. PM me with your ph. # and I'll walk you thru the diagnostic process.
Thread Starter
Race Director
Joined: Jun 2006
Posts: 17,901
Likes: 751
From: Inverness FL
St. Jude Donor '07
Russ
it's kind of a retro TPI; a modified Rochester FI with Accel Gen VII ECM and wideband O2 sensor.
it's kind of a retro TPI; a modified Rochester FI with Accel Gen VII ECM and wideband O2 sensor.
Bill
I checked your profile and it does not mention what type of injection you have, so if your's has modern sensors here's what the Ram Jet manual suggests to check.
1. OBD check, any codes set ?
no error codes
2. Check for correct base timing.
initial timing set at 12
3. Check for proper operation of fuel pump relay circuit.
5 sec prepressurization run at each start
4. Check for proper fuel pressure.
no gauge, but regulator set at 43 #
5. Check for proper ignition voltage output.
coil will burn water....
6. Check for a ECT(engine coolant temp) sensor shifted in value.
195 thermostat, verified by cylinder head temp sensor
7. Check MAP (Manifold absolute pressure) sensor for opens or shorts
to ground.
appears to read correct barometric pressure when key on, engine not running; and varies with engine speed & load
8. Check for proper operation of the TP (Throttle position) sensor.
was initially a problem, but has been corrected
9. Check for proper operation of the IAC (Idle air control) valve.
appears to be working, engine idles correctly and corrects for a/c compressor cycling
I realize that these are generic checks but the process for completing these checks are outlined in the manual.
I would also check your starter. I had a similar problem with my car, started fine but was slow to crank when hot. (mini starter) Turns out that one of the bridge wires on the brushes had broken and was making limited contact.
when cranking, you can hear/feel the engine 'grunting' occasionally while trying to start as if it is trying to compress a particularly rich cylinder(s). it would cold start, but absolutely positively not hot start until i leaned the high (rich) end (high MAP values) of the Volumetric Efficiency table by 25 - 30 %. now it starts HOT, but it's still not happy...(not overly happy cold either, but it starts too...)
Good luck
Russ
Bill
ps. PM me with your ph. # and I'll walk you thru the diagnostic process.
I checked your profile and it does not mention what type of injection you have, so if your's has modern sensors here's what the Ram Jet manual suggests to check.
1. OBD check, any codes set ?
no error codes
2. Check for correct base timing.
initial timing set at 12
3. Check for proper operation of fuel pump relay circuit.
5 sec prepressurization run at each start
4. Check for proper fuel pressure.
no gauge, but regulator set at 43 #
5. Check for proper ignition voltage output.
coil will burn water....
6. Check for a ECT(engine coolant temp) sensor shifted in value.
195 thermostat, verified by cylinder head temp sensor
7. Check MAP (Manifold absolute pressure) sensor for opens or shorts
to ground.
appears to read correct barometric pressure when key on, engine not running; and varies with engine speed & load
8. Check for proper operation of the TP (Throttle position) sensor.
was initially a problem, but has been corrected
9. Check for proper operation of the IAC (Idle air control) valve.
appears to be working, engine idles correctly and corrects for a/c compressor cycling
I realize that these are generic checks but the process for completing these checks are outlined in the manual.
I would also check your starter. I had a similar problem with my car, started fine but was slow to crank when hot. (mini starter) Turns out that one of the bridge wires on the brushes had broken and was making limited contact.
when cranking, you can hear/feel the engine 'grunting' occasionally while trying to start as if it is trying to compress a particularly rich cylinder(s). it would cold start, but absolutely positively not hot start until i leaned the high (rich) end (high MAP values) of the Volumetric Efficiency table by 25 - 30 %. now it starts HOT, but it's still not happy...(not overly happy cold either, but it starts too...)
Good luck
Russ
Bill
ps. PM me with your ph. # and I'll walk you thru the diagnostic process.
Last edited by wmf62; Jun 13, 2008 at 05:02 PM.
Burning Brakes
Joined: Dec 2004
Posts: 800
Likes: 3
From: Idaho
Bill
That is a very nice setup you have. It sounds like your up to speed on EFI and how it works. From what your discribing I would suspect a mechanical problem not associated with the EFI. If this is a new symptom that just started I would check for a stuck valve or a flat cam lobe. Also the ECT sensor that the manual refers to is the one that sends temp info to the ECM so that it can adjust fuel needs based on engine temp. Cold engine more fuel, warm engine less fuel. If the sensor has a shifted value it may be sending to much fuel to a warm engine during start up.
Good luck
Russ
That is a very nice setup you have. It sounds like your up to speed on EFI and how it works. From what your discribing I would suspect a mechanical problem not associated with the EFI. If this is a new symptom that just started I would check for a stuck valve or a flat cam lobe. Also the ECT sensor that the manual refers to is the one that sends temp info to the ECM so that it can adjust fuel needs based on engine temp. Cold engine more fuel, warm engine less fuel. If the sensor has a shifted value it may be sending to much fuel to a warm engine during start up.
Good luck
Russ
Pro
Joined: Mar 2002
Posts: 559
Likes: 0
From: Guelph Ontario
Cant you fire it up, shut it right down then check the plugs. A leaky injector should show up at the plug. Another method would be to prime the pump, shut the key back off and check for the fuel pressure to drop.
Very nice set up!
Very nice set up!
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Thread Starter
Race Director
Joined: Jun 2006
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From: Inverness FL
St. Jude Donor '07
if you've looked closely at my pic, you'll see that pulling plugs is not a fun job unless you have a hoist to get at them from underneath (and then #3 still really sux...)
fuel pressure could drop for other reasons than a leaky injector (pressure regulator, fuel pump check valve, etc)
actually, i think my primary problem is too much hot starting fuel (still could have a leaky injector though) as i can get it to start HOT if i lean out the high end of the VE table; but starting seems to be the big obstacle right now
Bill
Last edited by wmf62; Jun 14, 2008 at 10:49 AM.
Thread Starter
Race Director
Joined: Jun 2006
Posts: 17,901
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From: Inverness FL
St. Jude Donor '07
i understand the value of having a pressure gauge in the fuel loop, but i really don't like the look of it; i'm trying to keep as neat and as low key look as possible without calling more attention to the changes.
Bill
Le Mans Master
Joined: Sep 2003
Posts: 8,934
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From: Norwalk ohio
2019 Corvette of the Year Winner
St. Jude Donor '15
Bill, read the ECM manual again for the right thermostat to have. I thought for Gen VII ECM that they call out a 185 degree thermostat.....
Le Mans Master
Joined: Sep 2003
Posts: 8,934
Likes: 657
From: Norwalk ohio
2019 Corvette of the Year Winner
St. Jude Donor '15
you put in the big filter right? if so, then little chance of a leaky injector IMHO. Does your fuel circulate back to the tank through the fuel rails?
Race Director
Joined: Oct 2000
Posts: 15,104
Likes: 79
From: central FL, near the beach.
it is used for testing only. but, if it hurts your eyes too much, pull the plugs & replace any injector w/wet plug.
Last edited by Matt Gruber; Jun 14, 2008 at 10:15 AM.
Thread Starter
Race Director
Joined: Jun 2006
Posts: 17,901
Likes: 751
From: Inverness FL
St. Jude Donor '07
yes, i doubt that it would be any trash that could be causing an injector to leak as the entire fuel system is new and well filtered,
it would have to be a defective injector.
i'm still going through the 'tuning' phase and haven't really found a true 'expert' in tuning these things. everyone i talk to says how "easy" it is and everything i read says how difficult it is; and there are forums full of people bitching about it. by the same token, once it is 'dialed in'; people sing their praises..... and Accel's instructions leave a lot lot to be desired....
more of a 'how to' than a 'what if'.i don't remember seeing a thermostat temp suggestion/requirement in the literature i have (and i have printed and bound 100s of pages); can you point me to where that requirement is? BUT, i have found that it does run better hotter, when i changed from the 160 i used with the rochester to a 195 (the 160 never really ran 160 except in the winter, and i haven't have this system under those conditions..; probably in the 185ish + range and then higher when the a/c is on) it ran noticeably better. the problem is, it doesn't want to start HOT, and until i leaned out the high end of the 250 & 850 columns in the VE table by about 35%, it wouldn't start at all HOT. now it starts, but it's not happy....
Last edited by wmf62; Jun 14, 2008 at 10:47 AM.
Le Mans Master
Joined: Sep 2003
Posts: 8,934
Likes: 657
From: Norwalk ohio
2019 Corvette of the Year Winner
St. Jude Donor '15
Herb
yes, i doubt that it would be any trash that could be causing an injector to leak as the entire fuel system is new and well filtered,
it would have to be a defective injector.
i'm still going through the 'tuning' phase and haven't really found a true 'expert' in tuning these things. everyone i talk to says how "easy" it is and everything i read says how difficult it is; and there are forums full of people bitching about it. by the same token, once it is 'dialed in'; people sing their praises..... and Accel's instructions leave a lot lot to be desired.... more of a 'how to' than a 'what if'.
i don't remember seeing a thermostat temp suggestion/requirement in the literature i have (and i have printed and bound 100s of pages); can you point me to where that requirement is? BUT, i have found that it does run better hotter, when i changed from the 160 i used with the rochester to a 195 (the 160 never really ran 160 except in the winter, and i haven't have this system under those conditions..; probably in the 185ish + range and then higher when the a/c is on) it ran noticeably better. the problem is, it doesn't want to start HOT, and until i leaned out the high end of the 250 & 850 columns in the VE table by about 35%, it wouldn't start at all HOT. now it starts, but it's not happy....
yes, i doubt that it would be any trash that could be causing an injector to leak as the entire fuel system is new and well filtered,
it would have to be a defective injector.
i'm still going through the 'tuning' phase and haven't really found a true 'expert' in tuning these things. everyone i talk to says how "easy" it is and everything i read says how difficult it is; and there are forums full of people bitching about it. by the same token, once it is 'dialed in'; people sing their praises..... and Accel's instructions leave a lot lot to be desired....
more of a 'how to' than a 'what if'.i don't remember seeing a thermostat temp suggestion/requirement in the literature i have (and i have printed and bound 100s of pages); can you point me to where that requirement is? BUT, i have found that it does run better hotter, when i changed from the 160 i used with the rochester to a 195 (the 160 never really ran 160 except in the winter, and i haven't have this system under those conditions..; probably in the 185ish + range and then higher when the a/c is on) it ran noticeably better. the problem is, it doesn't want to start HOT, and until i leaned out the high end of the 250 & 850 columns in the VE table by about 35%, it wouldn't start at all HOT. now it starts, but it's not happy....
Thread Starter
Race Director
Joined: Jun 2006
Posts: 17,901
Likes: 751
From: Inverness FL
St. Jude Donor '07
i can chart/log and record and view on my laptop up to 6 sensors, for periods of up to several hours, as i drive. what i have been charting lately is knock retard, a/f ratio, rpm, engine temp, MAP %, and total timing; all of which are represented by separate curves on what amounts to a continuous digital strip chart. unless the ECM is nutz, a continuous readout of the engine temp is being provided by a passenger side cylinder head temp sensor; temps are from 199 to 210, depending on ambient temp, engine load, a/c, etc.... so, i don't believe i have a temp sensor problem..
fwiw, on a virtual dashboard i can view realtime: TPS, rpms, MAP psi, injector duty cysle & pulse width, a/f ratio, battery voltage, ignition timing, knock retard, closed loop correction, inlet air temp, and O2 correction.
Bill
Thread Starter
Race Director
Joined: Jun 2006
Posts: 17,901
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From: Inverness FL
St. Jude Donor '07
Bill