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Username Post: Ramjet 350        (Topic#344891)
Ramjet350 
Forum Newbie
Posts: 14

Reg: 05-22-17
05-22-17 04:56 PM - Post#2692337    

Just installed Ramjet 350 and won't start , spent an hour on the phone with GM tech support and he said bad ecm .... that over $600 dollars ..... would love to give to someone with the same motor to test for me .... it has oxygen sensor so it's the 4 . Anyone out there that can help ?



 




cbernhardt 
Senior Member
Posts: 561
cbernhardt
Loc: Lexington,NC
Reg: 08-28-00
05-23-17 07:27 AM - Post#2692459    
    In response to Ramjet350

Does the fuel pump run for a few seconds when you turn the ignition switch to "ON" - not "START"?
Have you checked the fuel pressure?
What is the serial number on the ECM?
Where are you located?



Edited by cbernhardt on 05-23-17 07:28 AM. Reason for edit: No reason given.

 
acardon 
Ultra Senior Member
Posts: 11010
acardon
Loc: DFW TEXAS
Reg: 03-25-05
05-23-17 07:41 AM - Post#2692462    
    In response to Ramjet350

I'm betting it's not the ECM. What vehicle is the Ramjet in? Do you have 12 volts ignition while cranking, as well as in start? Many GM techs don't understand "old car" wiring systems. Do you still have a ballest resistor or resistance wire?
Did the tech say what system in the ECM was bad?
It's not too likely, but a wiring error or short in the wiring can blow a ECM, so you end up with 2 bad ECMs. You need to trouble shoot down to a circuit and test that circuit before swapping ECM's.

Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)


 
monty56 
"14th Year" Gold Supporting Member
Posts: 1401
monty56
Loc: Chandler(it's a dry heat)...
Reg: 04-26-04
05-23-17 09:45 AM - Post#2692487    
    In response to acardon

I had to add a "timed" relay to the start because going from on to start the ECM lost power momentarily.

Monty
'56 3100 Short Stepside Someday
2001 Chevy Suburban 2500
2009 Saturn Vue w/20's

Member: Desert Classic Chevy's Inc.
Monty's 56 Truck
Avatar is my Truck


 
Ramjet350 
Forum Newbie
Posts: 14

Reg: 05-22-17
05-23-17 07:25 PM - Post#2692559    
    In response to cbernhardt

Cbernhardt .......Nope does not run at anytime , swamped relay to verify not bad relay . Fuel pressure when running pump of 12 volts is 45 pounds , tech said that should be good . Ecm has part number 88962717 , Malics # 565006. Numbers bottom right 11-025-11
Storm lake Iowa .



Edited by Ramjet350 on 05-23-17 07:26 PM. Reason for edit: No reason given.

 
Ramjet350 
Forum Newbie
Posts: 14

Reg: 05-22-17
05-23-17 07:33 PM - Post#2692561    
    In response to acardon

Acardon ....... . I have a hard time believing it's the ecm also , that is what the GM tech thought , all he had me check was spark , fuel pump operation , power and ground , I would lean more towards a sensor/wire not telling the ecm to activate/turn on the spark and or fuel , also the tester/programmer that comes with the ecm/harness has a led that barely eliminates ... leading me to think some sort of short . I have 12 volts on both ignition as well as during crank . I have replaced the 1977 steering column with a ididit column that uses relay pack to supply ignition , accessory and start . I pulled the harness back of the motor and looked for possible bare wires and or pinched wires , found nothing ....



 
Ramjet350 
Forum Newbie
Posts: 14

Reg: 05-22-17
05-23-17 07:35 PM - Post#2692562    
    In response to monty56

Monty 56 ... so are you running a ramjet 350 ? If so what ecm and where are you located if I may ask ?



 
cbernhardt 
Senior Member
Posts: 561
cbernhardt
Loc: Lexington,NC
Reg: 08-28-00
05-24-17 04:39 AM - Post#2692597    
    In response to Ramjet350

  • Ramjet350 Said:
Cbernhardt .......Nope does not run at anytime , swamped relay to verify not bad relay . Fuel pressure when running pump of 12 volts is 45 pounds , tech said that should be good . Ecm has part number 88962717 , Malics # 565006. Numbers bottom right 11-025-11
Storm lake Iowa .



Your part number indicates that the ECM is a MEFI4a. 45 psi is good.

My engine was originally an MEFI3 (no O2 or IAT sensor) which I converted to MEFI4a using the GM kit. In the MEFI4a installation instructions there is this information: "There are several different grounds on the new harness. The grounds must be grounded on separate studs on the engine. Failure to use separate ground studs may result in improper engine performance or ECM failure."

Have you checked your grounds?



 
acardon 
Ultra Senior Member
Posts: 11010
acardon
Loc: DFW TEXAS
Reg: 03-25-05
05-24-17 07:49 AM - Post#2692623    
    In response to Ramjet350

You have to have spark before the ECM will pulse the injectors. Do you have spark? The distributor and coil is a stand alone unit. It should provide spark even without the ECM, except it gets it's voltage from the ECM wiring.
Since you mentioned the LED on the tester, check for full battery voltage on the tester plug. Check the orange wire (terminal F) to engine ground for full battery voltage (12.6). Then check between the orange and black wire (terminal A) for the exact same voltage.
Do you have a tach connected? If so, disconnect it.
Check the distributor and coil plug for any bent pins. Here is a diagram of the distributor circuit. The 2 wire plug from the coil to the distributor supplies 12 volts to the distributor.
Here is a diagram of the distributor/coil. The wire "ign" is connected to wire A at the distributor. Check for 12 volts on wire A with it unpluged from the distributor.


Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)


 
monty56 
"14th Year" Gold Supporting Member
Posts: 1401
monty56
Loc: Chandler(it's a dry heat)...
Reg: 04-26-04
05-24-17 08:37 AM - Post#2692634    
    In response to Ramjet350

I'm in Chandler, AZ. and yes I am running a ramjet EFI on a 330 HO 350 Vortec. I have very few miles as yet as the body is in final assembly. I drove it about 8 blocks at the transmission shop to get the 700r set up. There are ground wires on the back of each head that must be separated and tight, and you need a good ground from engine to frame to body and back to battery or any combination of above.

Monty
'56 3100 Short Stepside Someday
2001 Chevy Suburban 2500
2009 Saturn Vue w/20's

Member: Desert Classic Chevy's Inc.
Monty's 56 Truck
Avatar is my Truck


 
Ramjet350 
Forum Newbie
Posts: 14

Reg: 05-22-17
05-24-17 02:46 PM - Post#2692698    
    In response to cbernhardt

Yep , all three grounds are separate bolt on head



 
acardon 
Ultra Senior Member
Posts: 11010
acardon
Loc: DFW TEXAS
Reg: 03-25-05
05-24-17 03:58 PM - Post#2692718    
    In response to Ramjet350

Do you have spark?

Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)


 
Ramjet350 
Forum Newbie
Posts: 14

Reg: 05-22-17
05-24-17 04:16 PM - Post#2692727    
    In response to acardon

No spark , has no power on pink wire .fuel pump relay base power on both constant and ignition ( according to gym tech negative is what ecm supplies to turn on relay ) the engine coolant sensor is suppose to have 5 volts input it has only 2.5 . The other sensors have no voltage ....



 
acardon 
Ultra Senior Member
Posts: 11010
acardon
Loc: DFW TEXAS
Reg: 03-25-05
05-24-17 04:31 PM - Post#2692733    
    In response to Ramjet350

It sounds like a wiring problem. The system relay doesn't get ground from the ECM. The relay has a constant ground and the ignition switch energizes the relay. Check the voltage on both ends of the inj/ecm fuse and the ECM/BAT fuses.

Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)


 
Ramjet350 
Forum Newbie
Posts: 14

Reg: 05-22-17
05-25-17 07:42 PM - Post#2692943    
    In response to acardon

According to the manual and on line the fuel relay has 4 wires . Orange is 12 volts constant , pink is 12 volts ignition , gray wire is fuel pump positive and green with white is ground activation wire from ecm .



 
acardon 
Ultra Senior Member
Posts: 11010
acardon
Loc: DFW TEXAS
Reg: 03-25-05
05-26-17 11:34 AM - Post#2693044    
    In response to Ramjet350

That's right, but the fuel pump relay doesn't play a part until you get spark. Are these voltages there??? You HAVE to have spark first. The ECM SYSTEM relay does not depend on the ECM to operate. The ignition switch energizes the system relay which is connected directly to ground on a black wire. The system relay provides power to the coil and fuel pump relay as well as the rest of the ECM. The system relay is connected directly to the inj/ECM fuse. If you have power there we can trouble shoot farther. There is a soldered splice in the harness that may have broken loose and loosing power to the coil. As I mentioned, the distributor/coil is a stand alone unit that provides SPARK to the plugs and timing signals to the ECM.

Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)


Edited by acardon on 05-26-17 11:35 AM. Reason for edit: No reason given.

 
Ramjet350 
Forum Newbie
Posts: 14

Reg: 05-22-17
05-26-17 06:53 PM - Post#2693082    
    In response to acardon

Plugged in new ecm , started right up ..... finally



 




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