How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Mike Your Own Question
Mike, Technician
Category: Car
Satisfied Customers: 39198
Experience:  Tech Expert
Type Your Car Question Here...
Mike is online now
This answer was rated:

I have just restored a 1970 Aston Martin DBS V8I fitted with

a Bosch mechanical fuel injection... Show More
a Bosch mechanical fuel injection unit but the car lacks power under acceleration We have checked the ignition settings including advance and retard, injector pump timing valve timing fuel pump supplyThe bosch pump has been serviced by their agents and can find no problems.We have run the car with a CO meter-at idle it reads 5.5-6 If I Floor the accelerator from 1500 to 2000 RPM( while being driven ) the reading drops back to 1 -at this point it pops back through the air cleaner and misses If I release the accelerator it immediatly goes back up to 6 We have tried adjusting the main rack but this does not solve the problem The throttle and injector pump linkages are set according to the manual It is obviously starving itself of fuel under acceleration Hope you can help Roger
Show Less
Ask Your Own Car Question
Hello Roger,
I'm Shantal and I'm a moderator for this topic.
I've been working hard to find a Professional to assist you with your question, but sometimes finding the right Professional can take a little longer than expected.
I was checking to see if you had already found your answer or if you still need assistance from one of the Professionals.
Please let me know if you wish to continue waiting or if you would like for us to close your question?
Thank you,
Customer reply replied 2 years ago.

Your reply went into spam folder Yes I still need a reply to my question


***** *****

Hello Roger -
My name is***** a tech and happy to help you from here.
Before we go into this Roger - please just confirm re the above, that you are actually receiving my message to you - then we can carry on from here -
Best Rgds, MIKE...........................
Customer reply replied 2 years ago.

Hi Mike

I received your E Mail.Look forward to your response

Hi there Roger..
Thank you for your reply.. thats great.
I would say having read this through Roger , you need to connect up a fuel pressure test kit and see exactly whats going on there. I suspect as you do that this is a fuelling thats the best way forward - best next step on this one to make progress.
If it were backfiring, ( and this may fit your symptoms ) I would also check / suspect the ignition timing... may be worth checking still - checking the advance / retard feature in the distributor... this is / was a common fault. Too - check the vac advance unit while you are there--
Many people changed them over to electronic ign to combat such running issues caused by such issues - I don't know what you have of course so I mention it just in case-
I assume you have checked / dealt with such as fuel supply - ie, fuel filters - and air ingress etc - made sure thats all ok / correct.. After that - you are back to the above. I know you mentioned some of these things but something in that little lot has to have been really there is nothing else that could be causing this on this system
Let me know how you go..and / or let me know if you need anything further on this..
~>>~~~ Meantime - Please do click on the "Exc / Ok rating" for me at this time.. "Thank you" in advance for that .
.. Note that you can get back to me anytime at all after doing the rating - it doesn't close you out --
Best Rgds, MIKE.
Customer reply replied 2 years ago.

Hi Mike

Thanks for the prompt response .Inreply to your suggestions-Fuel pump pressure10psi-flow is ample.Timing with timing light-at idle going up to25-28 degrees before TDC before at 3000rpm If the vacumn pipe is removed at idle it moves to 15 before TDC.We have checked thoroughlyfor air leaks The missing happens only on hard acceleration between 1500 and 2000 rpm under load ie when passing The COs read 6% at idle but drop to 1% if the throttle is floored If it is released they jump back up to 6% at any speed I understand there is a govenor built into the injector pump to enrich the fuel under acceleration - it has to be set by a specialist The Bosch agent checked the pump but said it was working OK but would not have ckecked the govenor If we cannot sort the problem I will consider electronic but at this stage i want to keep it original I will be away 4days so cannot answer your reply



Hello again Roger -
Thank you for your reply --
Ok Roger - Ive got some info for that might help - by way of a site of the AMOC.. I don't know if you know it / heard of it.. but I think it would be helpful for you --take time to read through etc.. there's a lot of info there that could help you ..
The web address is:
Sorry I cant link you - you will need to copy / paste into your browser...
I hope that helps you more so -
Best Rgds, MIKE.
Customer reply replied 2 years ago.

Hi Mike

have downloaded the website you recommended-Will see how we get on