5.7GSi starts then stalls
03-18-2014, 06:29 PM
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5.7GSi starts then stalls
Hello,
I am working on a 5.7GSi Volvo motor. The motor has just been replaced and we are having issues with it starting and then quitting after about 15-20 seconds. The last owner had plugged manifolds and heated up the motor to a point where he lost two cylinders, hence the new motor. What's funny is that I can put 10"of vacuum on the MAP sensor and the motor will run all day, but as soon as I pull off the vacuum off and plug in the vacuum hose from the back of the TBI it stalls out and dies. With the vacuum on the map sensor I have the timing set, new low and high pressure fuel pumps, f/w sep, running on a good fuel source. Testing of the systems showed the MAP sensor is fine, fuel pressure regulator is fine. All grounds and power ending have been cleaned and tightened. Has anyone had this issue? Or could anyone point me in a direction besides in circles. Thank you
I am working on a 5.7GSi Volvo motor. The motor has just been replaced and we are having issues with it starting and then quitting after about 15-20 seconds. The last owner had plugged manifolds and heated up the motor to a point where he lost two cylinders, hence the new motor. What's funny is that I can put 10"of vacuum on the MAP sensor and the motor will run all day, but as soon as I pull off the vacuum off and plug in the vacuum hose from the back of the TBI it stalls out and dies. With the vacuum on the map sensor I have the timing set, new low and high pressure fuel pumps, f/w sep, running on a good fuel source. Testing of the systems showed the MAP sensor is fine, fuel pressure regulator is fine. All grounds and power ending have been cleaned and tightened. Has anyone had this issue? Or could anyone point me in a direction besides in circles. Thank you
03-18-2014, 09:16 PM
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what is your fuel pressure with key on and with the motor running ? Also what is MAP voltage and what scan tool are you using ?
Problems with TBI and Volvos - Cool fuel cell meaning the fuel pumps, TPS, MAP, IAC, and of course TBI injectors need to be flow tested and cleaned then flow tested again. We offer that service as well.
How did you install the high pressure fuel pump in the fuel cell. You can easly install the low pressure pump but not easy at all to install the high pressure fuel pump. I have never seen it done correctly and that's why Volvo only sells the complete unit - cool fuel cell with the fuel pumps already installed along with the fuel water sep filter installed as well. it retails for 900 bucks.
Also Volvo has a SB to install the whole unit not just the fuel pumps. Also what I really want to know how are testing the map sensor and what are your specs at idle and at full throttle. IMO you need a new map sensor and possible fuel injectors flow tested & cleaned.
Problems with TBI and Volvos - Cool fuel cell meaning the fuel pumps, TPS, MAP, IAC, and of course TBI injectors need to be flow tested and cleaned then flow tested again. We offer that service as well.
How did you install the high pressure fuel pump in the fuel cell. You can easly install the low pressure pump but not easy at all to install the high pressure fuel pump. I have never seen it done correctly and that's why Volvo only sells the complete unit - cool fuel cell with the fuel pumps already installed along with the fuel water sep filter installed as well. it retails for 900 bucks.
Also Volvo has a SB to install the whole unit not just the fuel pumps. Also what I really want to know how are testing the map sensor and what are your specs at idle and at full throttle. IMO you need a new map sensor and possible fuel injectors flow tested & cleaned.
Last edited by BUP; 03-18-2014 at 09:28 PM.
03-18-2014, 10:25 PM
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Thank you for the replies, I have no smoke machine but I have an idea about how I could go about that. As for the high pressure fuel pump, it is located on top of the VST tank on the rear of the motor supplying fuel straight to the TBI.
Fuel pressure- key on, low pump is about 8psi off the VST and the high pump is 19psi. With the motor running there isn't much difference in the fuel pressure. As for testing the MAP sensor. I plugged into the back of the connector while installed on the MAP with my DVM and hooked up a manual vacuum pump to the sensor. At 10"of vacuum I had 2 volts and at 25" of vacuum it was 4.5 volts. I did not check the readings while running because of how the motor will only run for a few seconds while the main vacuum line was connected.
On another side note, the motor is drawing 15" of vacuum from the TBI vacuum hose. If having all vacuum lines connected and we get the motor started, we can increase the rpms to around the 3000 rpm mark and the motor will run then. but as soon as we return to idle the motor stalls.
The motor is in a 1988 Bayliner that had a OMC motor in it. Then they replaced it with a 5.7GSi Volvo Penta motor and we are guessing it is about the 1998 model year for motor electronics.
I do not have a scan tool for this motor yet either, I checked the DTC codes by jumping the timing mode connections in the DLC connector and installed a LED light in the far left terminals of the DLC.
Fuel pressure- key on, low pump is about 8psi off the VST and the high pump is 19psi. With the motor running there isn't much difference in the fuel pressure. As for testing the MAP sensor. I plugged into the back of the connector while installed on the MAP with my DVM and hooked up a manual vacuum pump to the sensor. At 10"of vacuum I had 2 volts and at 25" of vacuum it was 4.5 volts. I did not check the readings while running because of how the motor will only run for a few seconds while the main vacuum line was connected.
On another side note, the motor is drawing 15" of vacuum from the TBI vacuum hose. If having all vacuum lines connected and we get the motor started, we can increase the rpms to around the 3000 rpm mark and the motor will run then. but as soon as we return to idle the motor stalls.
The motor is in a 1988 Bayliner that had a OMC motor in it. Then they replaced it with a 5.7GSi Volvo Penta motor and we are guessing it is about the 1998 model year for motor electronics.
I do not have a scan tool for this motor yet either, I checked the DTC codes by jumping the timing mode connections in the DLC connector and installed a LED light in the far left terminals of the DLC.
03-19-2014, 10:31 AM
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Your high pressure fuel pump the fuel pressure is too low. Also the ECM sends a 5 volt reference signal to the MAP sensor. As the manifold pressure changes the electric resistance of the MAP sensor also changes. You have to montor the sensor output voltage. So what you really need is a scan tool. Sorry you are chasing your tail and if you are working on boats especially for living you really need a scan tool. Diacom is your best bet. Also some other scan tool providers are STATS by SIerra and MEDS by CDI.. AND of course older DDT from Mercruiser and OTC along with CDS thru Merc and SPX.
Next I have a professional fuel injector testing and cleaning Machine. It has a real back flush system also, IMO cleans injectors better than machines that do not have a real back flush unit. ASNU does not has this in their app and my machine is not a ASNU. I have used the ASNU machine and I think is just average.
I have been doing this service for almost 5 years - mostly for boat dealers around the USA. Anyways I have references if anyone needs them from the dealers that are my customers. I did put a post up here about it and gave some good info on top of. I will try to find the link and post it. Good Luck.
Next I have a professional fuel injector testing and cleaning Machine. It has a real back flush system also, IMO cleans injectors better than machines that do not have a real back flush unit. ASNU does not has this in their app and my machine is not a ASNU. I have used the ASNU machine and I think is just average.
I have been doing this service for almost 5 years - mostly for boat dealers around the USA. Anyways I have references if anyone needs them from the dealers that are my customers. I did put a post up here about it and gave some good info on top of. I will try to find the link and post it. Good Luck.
Last edited by BUP; 03-19-2014 at 10:55 AM.
04-04-2014, 11:43 PM
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For those of you not on Amtech......Sorry about how long it has taken to get back on here to update the situation but he have a fix for our problem....So we got the diagnostic cable from CDI for the MEFI 1-4. The computer readings were all fine except for we had a MAP sensor issue. Replaced MAP sensor. No other issues with that. Spray pattern from the injectors were nice, cone shaped. No other fuel leaks in the system or plugged lines and replaced the F/W Sep filter. Testing the output from the high pressure fuel pump gave us 60 PSI. High pressure pump fine. Attaching pressure gauge to the check valve and a gauge to the end of the return line to the VST with the key on would give us a reading of 60 PSI on the check valve and 40 PSI on the return line. Once everything else was connected back to their proper locations, our pressure reading on the check valve with the key on would only be 17-19PSI for fuel pressure. We contacted the owner of the boat and told him we had narrowed it down to the fuel pressure regulator to which he contacted the seller of the TBI he installed on the motor (some company from Florida) and he was told that they did not know the high pressure fuel pump put out that much pressure. To make a long story short, we received a new TBI, installed it, and it ran like a charm. The fuel pressure held steady at 30 PSI from the check valve. And no additional codes on the computer. I would like to thank you all for your inputs and advice regarding this issue.
