savageoutlaw Posted June 26, 2012 Share Posted June 26, 2012 Something that I have noticed with my Datsun, is that when I accelerate (In a hurry anyways) is that it sounds as if the fuel is cutting out. The engine goes then is silent and goes (In quick recessions). It goes back to normal when I take foot off accelerator and then accelerate again. Is this just me going to hard on it or is there something wrong with the fuel pump? Running A15 engine with electronic fuel pump. Sorry if its a stupid question, Not the most car savvy person. Quote Link to comment Share on other sites More sharing options...
KKtrips Posted June 26, 2012 Share Posted June 26, 2012 Most probably a good tune will take care of this. May be a carb issue but at least a good tune will eliminate it.. Quote Link to comment Share on other sites More sharing options...
savageoutlaw Posted June 26, 2012 Author Share Posted June 26, 2012 Thanks, I will look into that. I get the car back from Mechanic in a few days. (new exhaust) Hes cleaned the carburettors too, so if that hasn't fixed it I'll let you know. Also have got NO experience on tuning.. Yet anyways. Quote Link to comment Share on other sites More sharing options...
cletus Posted June 27, 2012 Share Posted June 27, 2012 if its a fuel pump weak/flow issue, it will accelerate normally for a bit then start cutting out, as it takes some time to drain the carb bowl Quote Link to comment Share on other sites More sharing options...
Llama Posted June 27, 2012 Share Posted June 27, 2012 Probably what's happening is that as soon as you open the throttle plate, the low pressure that was in the manifold (high vacuum) is very quickly brought up to atmospheric (low vacuum). This causes the much of the fuel that is in the manifold heading to the engine to condense out and stick to the manifold walls, hence you run lean for a bit until the flow from the carb catches up. How to fix it on a A15? No clue Aside from what has already been said, does it have an accelerator pump on the carb? Quote Link to comment Share on other sites More sharing options...
KKtrips Posted June 27, 2012 Share Posted June 27, 2012 Overcomplicating it matey. I would be sorting the basics first. Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted July 2, 2012 Share Posted July 2, 2012 Has it got the jap SU carb copies like some other datsuns? If so it could be the oil level for the damper on the top of carb/s is a touch low. If the piston at the bottom of the rod is not at least touching the oil then you will have some undamped movement and the piston will lift too quick and lean the mixture out enough that the car will bog down. Quote Link to comment Share on other sites More sharing options...
savageoutlaw Posted July 2, 2012 Author Share Posted July 2, 2012 Thanks for the ideas guys. Will try out some fixes when I get the car back later in the week. (Getting new extractors and exhaust installed) It has an electric fuel pump where the wiring used to play up and Hitachi twin SU style carbs. (Which I'm still looking for air filters to suit) . Quote Link to comment Share on other sites More sharing options...
azzurro Posted July 2, 2012 Share Posted July 2, 2012 unsure on SUs but webers/dellortos like to have a restrictor to limit the incoming fuel pressure otherwise the needle valves cant shut off leading to just as many problems as a weak supply. so, your electric fuel pump could be providing too much fuel pressure to the carbs, so your bogging could be flooding? Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted July 2, 2012 Share Posted July 2, 2012 Yep defrost check those oil levels in carb dampers. My viva started to bog down when I would pull away needing me to ride clutch. I checked oil level in carb and it looked ok but was actually about 5 mm to low. Hence the very first bit of piston lift on the carb was un-damped. Topped oil up= transformation. Quote Link to comment Share on other sites More sharing options...
felixx Posted July 2, 2012 Share Posted July 2, 2012 azzuro, how could we reduce pressure from fuel pump? Would that require some form of regulator? fake edit: other than crimping/ tying a knot in the fuel line? Quote Link to comment Share on other sites More sharing options...
azzurro Posted July 2, 2012 Share Posted July 2, 2012 Yep a regulator, or better yet a fuel pump that provides the correct pressure (so your not wasting money by restricting your fancy new pump). I think webers like no more than 4 psi. They do like volume, but not under pressure. Not a problem ive actually had to resolve myself, just been reading up on carbies a lot lately and I read that high pressure leccy fuel pumps (esp those designed for FI) are often an overlooked cause of problems on carburetted fuel systems. Sometimes more is not always better. Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted July 2, 2012 Share Posted July 2, 2012 I run a simple but effective Malpassi reg to keep below 3psi limit on my SU. Quote Link to comment Share on other sites More sharing options...
felixx Posted July 2, 2012 Share Posted July 2, 2012 OK. I will help Andrew fit one. Cheers Guys. Would something like this be what he needs? http://www.trademe.co.nz/Trade-Me-Motors/Car-parts-accessories/Performance/Fuel-systems/photos/a-489698174/p-197631753.htm $75 Quote Link to comment Share on other sites More sharing options...
smokin' joe Posted July 2, 2012 Share Posted July 2, 2012 OK. I will help Andrew fit one.Cheers Guys. Would something like this be what he needs? http://www.trademe.co.nz/Trade-Me-Motors/Car-parts-accessories/Performance/Fuel-systems/photos/a-489698174/p-197631753.htm $75 looks like one you would use on an EFI set-up. what pump are you using? is it a facet or similar Quote Link to comment Share on other sites More sharing options...
smokin' joe Posted July 2, 2012 Share Posted July 2, 2012 this is what i am fuelling twin 40 DHLA's in the Te71, although probably dosn't really need the reulator, if using a return line ( I am not ) http://www.fuelflow.co.nz/FF_cms_03/esh ... gory_id=28 http://www.fuelpumpsonline.co.uk/sytec- ... r-30-p.asp used to have a Facet Red pump in the car, and had similar issues with bogging on acceleration, these may have been prevented with either a regulator, or a return line Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted July 2, 2012 Share Posted July 2, 2012 It took a while before I found the right reg at a decent price. Most were for much higher pressures. Most i spoke to recommended malpassi for being reliable (but a bit pricey) http://www.palmside.co.nz/product_pcid_15786.html I got a good second hand one for $50ish. Not a lot to go wrong with them. Quote Link to comment Share on other sites More sharing options...
azzurro Posted July 2, 2012 Share Posted July 2, 2012 You could test before you buy a regulator with vice grips or hoseclamps or a kinks and see if the symtoms change? Quote Link to comment Share on other sites More sharing options...
smokin' joe Posted July 2, 2012 Share Posted July 2, 2012 You could test before you buy a regulator with vice grips or hoseclamps or a kinks and see if the symtoms change? wouldn't that method just restrict flow?? Quote Link to comment Share on other sites More sharing options...
azzurro Posted July 2, 2012 Share Posted July 2, 2012 yes Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.