Hopefully I don't perform any big sins since I don't have truck, but engine is from one. It's -91 350 TBI that is controlled by Megasquirt2 and has also wasted spark ignition.
Problem is that when starting hot and engine has been sitting short while (maybe 5-15mins) the engine seems to back fire/pop to intake. If engine has been sitting long enough maybe 30mins+ or overnight starting is no problem. I've been running for 8 years and seems that this summer it's getting worse so I started finally inspecting more.
I suspected that fuel is leaking to intake when turning engine off and due wasted spark the wrong cylinder has combustible mix and that cause the pop/backfire when starting. I thought that maybe the injectors maybe leaking. I ran the fuel pump today when engine wasn't running, but I could not see any fuel leak either from injectors or anywhere else, but when I opened butterflies completely I could see fuel pooled at the bottom of the intake under both butterflies.. I tested it with q-tip and it smelled like gas not antifreeze.
Now I'm puzzled where that gas is leaking from. Is there a path under the TBI where it could leak? I've taken it apart few years back but can't remember anymore. I don't think there should be any path under for gas to leak?
Problem is that when starting hot and engine has been sitting short while (maybe 5-15mins) the engine seems to back fire/pop to intake. If engine has been sitting long enough maybe 30mins+ or overnight starting is no problem. I've been running for 8 years and seems that this summer it's getting worse so I started finally inspecting more.
I suspected that fuel is leaking to intake when turning engine off and due wasted spark the wrong cylinder has combustible mix and that cause the pop/backfire when starting. I thought that maybe the injectors maybe leaking. I ran the fuel pump today when engine wasn't running, but I could not see any fuel leak either from injectors or anywhere else, but when I opened butterflies completely I could see fuel pooled at the bottom of the intake under both butterflies.. I tested it with q-tip and it smelled like gas not antifreeze.
Now I'm puzzled where that gas is leaking from. Is there a path under the TBI where it could leak? I've taken it apart few years back but can't remember anymore. I don't think there should be any path under for gas to leak?
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