5.7gi reman shutting off on test stand

[Galvez83]

Reman 5.7gi started on a stand will idle but once rpms are up it will hesitate, bucking and even want to shut off or it will shut off. It will sometimes also backfire. Several parts are new before starting due to deteriorated such as starter, distributor, oil sender, circ pump, knock sensor, fuel and oil filters, harmonic balancer, risers, plugs and wires. Mefi 3 was also sent off to be calibrated for a 5.7 from a 5.0. Engine is currently using a 5 gal can to start with. Noticed left riser getting hotter than the right one but could not find my temp gun to see the actual temp but engine was shut off due to concern. Any ideas what could be causing the hesitation/cut off upon higher rpms?

 

[Bondo]

Reman 5.7gi started on a stand will idle but once rpms are up it will hesitate, bucking and even want to shut off or it will shut off. It will sometimes also backfire. Several parts are new before starting due to deteriorated such as starter, distributor, oil sender, circ pump, knock sensor, fuel and oil filters, harmonic balancer, risers, plugs and wires. Mefi 3 was also sent off to be calibrated for a 5.7 from a 5.0. Engine is currently using a 5 gal can to start with. Noticed left riser getting hotter than the right one but could not find my temp gun to see the actual temp but engine was shut off due to concern. Any ideas what could be causing the hesitation/cut off upon higher rpms?

Ayuh,.... Sure sounds like it's starvin' for fuel,....

Test yer fuel pump pressure,....

 

[Galvez83]

Bondo i just tested both pumps. Lower comes in at about 18 psi constant at idle and load. High side comes in at about 33 psi constant at idle and load. Aftet testing the schrader valves started leaking after engine shut off. This is a carter pump and being a new to me boat i would like to change both schrader valves but cant find the right part number. I know if i buy a new fuel unit it comes with the low side but not the high i would still need it for the high side. Engine still backfiring and wants to shut off and sometimes it will shut off as i give it slight throttle and watched the gauges. Any ideas?

 

[alldodge]

Assuming your using the injectors from the 5.0, which Gi was it?

Do you know which fuel tables where used for the remaping of the fuel tables?
Reason for asking, is the tables are different depending on which injectors and the pressures are used. The 5.0 Gi can be from 30 to 60 psi, and the 5.7 Gi can be from 11 to 60 psi

 

[Galvez83]

Assuming your using the injectors from the 5.0, which Gi was it?

Do you know which fuel tables where used for the remaping of the fuel tables?
Reason for asking, is the tables are different depending on which injectors and the pressures are used. The 5.0 Gi can be from 30 to 60 psi, and the 5.7 Gi can be from 11 to 60 psi

View attachment 367940

Yes i am using the same injectors. I don't really know the fuel tables used when remapping, i would have to ask Ben Bowman to see. To accompany this i did another compression test with an Innova gauge because the Harbor freight was giving way low numbers and this is what i got with all plugs off.

 

[Galvez83]

5.0gi PEFS, i sent a message to the reprogramer to see if there was a need to have injectors replaced. Either way if not needed i will still have injectors flow tested and cleaned. I also removed spark plugs (ACDELCO MR43LTS) and reviewed that gaps. Some plugs with gaps of 45° and some with 30°. I regapped them all 45° and still no improvement.

 

[alldodge]

Compression numbers are not within 10% low to high but are good enough to run fairly well

EST ignition, was it placed in base timing mode to set timing?

Is there a place to connect a vacuum gauge?

 

[Galvez83]

On a rebuilt i questioned the weird compression on some cyls but we did have an issue with loose valves that needed to be 0 lashed again. There is a vacuum port at the TBI leading to the MAP. I jumpered the DTC blk and blk and white and got it in the ballpark but no timing light used.

 

[alldodge]

Tee into the fitting and see if your get 18 or above in Hg

 

[Galvez83]

Any specifics as to how to perform the test such as engine on or off, specific rpms?

 

[alldodge]

Motor at idle, and vacuum should be steady, needle not shaking any

How about the timing

 

[Scott06]

On a rebuilt i questioned the weird compression on some cyls but we did have an issue with loose valves that needed to be 0 lashed again. There is a vacuum port at the TBI leading to the MAP. I jumpered the DTC blk and blk and white and got it in the ballpark but no timing light used.

Use a timing light

 

[Galvez83]

Will do so, just a heads up as to what the engine does. This vid is not mine. The difference is that mine does start up and stays fine at idle only when rpms are high and mine is outside the boat using a 10 gal gas can.

 

[alldodge]

Have you checked for any codes?

Check for 12V at the injectors when key is ON and while cranking

Measure TPS voltage. Should be 0.6V or tad higher. If its at 2.5V or higher then its in clear flood mode

The ECM fires the injectors based on info received from the Dizzy. If signal is not getting to the ECM or if its weak due to a bad connection there will be no fuel released. Check for Tach signal with a Test light to see if it goes from bright to dim while cranking J2-8