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2007 ie Breva starting problems

B

bobsbreva750

Just got it firing!
Joined
Dec 5, 2013
Messages
16
Location
South Daytona
So, I have finally sorted my 2007 Breva-engined kit car conversion to the point where the motor idles and runs pretty well.

I had to totally relocate all the major fuel injection components, instrument panel, ECU and engine connections and make up a new wiring harness. I had to extend the intake manifolds and throttle bodies because of engine mounting problems. Also I had to make a new oil breather because I couldn't fit the OEM Breva airbox into the engine compartment.

What I need some help on is that the motor will not start when cold till after about 3-5 minutes of cranking and working the throttle. When warm the motor will start instantly. I have a Centurion analyzer and have been able to balance the throttle bodies at 3800 rpm's and the idle at 1000 rpm's and further reset the TPS at 3.1. There are a number of other parameters the Centurion displays but how do I know if those numbers are normal? I have the fuel pressure regulator set at 41 psi and no trouble codes appear on the Centurion DTC page.

I do not have a balance tube between the exhaust manifolds because I haven't figured out how and where to fit it in the the increasingly confined engine compartment spaces. I do have the lambda sensor fitted into the right-hand exhaust manifold and the air temperature thermistors and cylinder head temperature sensor connected. It appears that all the sensors are operating and sending data to the the ECU.

The spark plugs are BR8ES as called for in the manual and the coils, injectors and fuel pump seem to be operating correctly when tested with the Centurion. When I try to start the engine when cold it seems to fire but will not sustain ignition. Of course, being in Florida I am not talking about freezing cold, just about 50-60 degrees.

Any and all suggestions will be greatly appreciated. Please refer to a previous post to see a picture of my conversion configuration.

bobsbreva750
 
On a cold engine, what are the engine and air temperatures being reported by the ECU to Centurion? Are the injectors in their original position close to the heads?

If the temperature readings are in range, the 750 Breva is a notoriously cold blooded engine. Start cranking with the throttle closed and gradually open the throttle a little. See if that helps.
 
I agree with John's answer on all counts; the Guzzi 750 is hard to start when cold although your example is extreme.

I add that some people have found this routine helps cold starts: crank for 3-5 seconds with the throttle wide open. Then start it with the throttle almost closed, i.e. open slightly by the "choke" or throttle stop lever.

And...in setting up the engine did you include the choke/throttle stop mechanism?
 
John: The injectors are mounted in the original position. Temperatures being reported to the Centurion are the air temperature in the shop. I only moved the throttle bodies back about 10". And, sign216. I do have the throttle/stop mechanism incorporated. I'm off to the shop to try your suggestions.
Thanks,
bobsbreva750
 
bobsbreva750 said:
John: The injectors are mounted in the original position. Temperatures being reported to the Centurion are the air temperature in the shop. I only moved the throttle bodies back about 10". And, sign216. I do have the throttle/stop mechanism incorporated. I'm off to the shop to try your suggestions.
Thanks,
bobsbreva750
Click to expand...

Sounds like the engine temp sensor is delivering correct information. The injectors mount in the throttle body. So they are not in their original position in relation to the intake valve. With the TBs back that far you may not be getting enough turbulence to get a good fuel mix delivered to the engine. Some of the fuel droplets may not be making it into the cylinder. Air speed and manifold vacuum are your friend when trying to get a good combustible mix.

If you can't get the TBs back where they were you may need to add a priming circuit closer to the engine for cold starts. This was not an uncommon practice in the early 1900s. Most engines then used updraft carb setups. Systems were developed to add a little fuel to the manifold closer to the combustion chamber. In the 1980s some cars (SAAB for one) had an additional injector that would deliver additional fuel for cold starts.
 
John: My injectors are mounted in the intake manifolds in their original location on the cylinder heads. Anyway, I used your suggestions for starting and had much success. While cold the throttle pedal had to be used till the engine was warm enough to idle properly. After that all was well. Thanks for the ideas. Still a lot of buttoning-up to do but I was ablr to go for my first test ride yesterday. A good day.
bobsbreva750
 

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Well, I did get the engine started and it runs pretty good. So far I have three test drives completed, each one longer than the rest. Yesterday I survived a short run on International Speedway Boulevard mixed in with Daytona Bike Week traffic. There are a couple of videos I posted to You Tube under the search tag "Pembleton Super Guzzi", titled, " 20140313 153636" and "20140305 150338 Copy".
bobsbreva750
 
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